205.松尾山城 その1

1600年(慶長5年)9月15日に起こった関ヶ原合戦は、日本史で最も重要な出来事の一つですが、そのハイライトといえば何でしょうか。これまでの通説に従えば、何といっても小早川秀秋の「裏切り」でしょう。しかし近年、秀秋の「裏切り」には疑念が挟まれています。数少ない信頼できる史料を再検討し、関ヶ原合戦を再構成する取り組みが行われています。

立地と歴史

Introduction

1600年(慶長5年)9月15日に起こった関ヶ原合戦は、日本史で最も重要な出来事の一つですが、そのハイライトといえば何でしょうか。これまでの通説に従えば、何といっても小早川秀秋の「裏切り」でしょう。秀秋は、関ヶ原南方の松尾山城に陣を布き、合戦が始まってもなお東軍につくか、西軍につくか明らかにしていませんでした。そして、しびれを切らした東軍の総帥・徳川家康の命による「問鉄砲」に刺激され、ついに東軍に組みし、その勝利に貢献したというストーリーです。

「関ヶ原合戦図屏風」、関ケ原町歴史民俗資料館蔵 (licensed under Public Domain via Wikimedia Commons)

しかし近年、秀秋の「裏切り」と「問鉄砲」には疑念が挟まれています(白峰旬氏などの指摘)。関ヶ原合戦の記録は、同時代の当事者が記した一次史料がとても少なく、大半は後の時代に記された二次史料に頼っているからです。例えば、「問鉄砲」の記述は、合戦から半世紀以上後の軍記物「慶長軍記」からとのことです(呉座勇一氏による)。「問鉄砲」の事実が揺らぐと、秀秋の「裏切り」のタイミングも、本当に合戦の最中だったのか怪しくなってしまいます。また、秀秋がどのように松尾山城に着陣し、いつ東軍に味方する決断をしたのかとういことも謎めいてきます。最近は、その少ない一次史料・それに準ずるものを再検討し、関ヶ原合戦を再構成する取り組みが行われています。それにより、「問鉄砲」の見直し以外にも、いくつも新説が提起されています。それに松尾山城については、通常は小早川秀秋陣と言われますが、そもそも何のために築かれ、使われるはずだったのかも気になります。

小早川秀秋肖像画、高台寺蔵 (licensed under Public Domain via Wikimedia Commons)

そこで、この記事では、小早川秀秋と松尾山城との関わりについて、主に3つの視点をもって、従来説を含めた3つの仮説にまとめて、ご紹介したいと思います。
3つの視点とは、
a.関ヶ原合戦前、秀秋はどこで何をしていたのか。
b.なぜ関ヶ原が決戦場となり、秀秋はいつどのように松尾山城に布陣したのか。また西軍諸将はどこに布陣したのか。
c.秀秋は、いつ東軍に加わると決心したのか。
3つの仮説とは、
1.「問鉄砲」を含む従来説
2.小早川秀秋は裏切っていないとする説
3.西軍が松尾山城攻めをしたとする説
です。

ただしまずは、小早川秀秋と松尾山城の、関ヶ原合戦に至るまでの来歴を、簡単にご紹介してから、各説のパートに入ります。

関ヶ原に至るまでの小早川秀秋と松尾山城

秀秋は、豊臣秀吉の妻・北政所の兄、木下家定の五男として1582年(天正10年)に生まれたとされています(足守木下家譜)。幼少の頃より秀吉の養子となり、北政所に養育されていたようです。その当時から秀吉から「きん吾」と呼ばれていました(天正13年閏8月秀吉書状)。そしてわずか7歳のときに元服し、従五位下・侍従(公家成)になり、秀吉の後継者候補の一人として扱われました。秀吉が天下を取った頃には、権中納言に昇進(13歳)、丹波亀山城主にもなっていました。ところが、文禄2年に秀吉の実子・秀頼が誕生すると、翌年に秀秋は、小早川家に養子に出されてしまいます。秀吉が、秀頼の後継者としての地位を安泰にしようとしたためと考えられます。

木下家定肖像画、建仁寺常光院蔵 (licensed under Public Domain via Wikimedia Commons)

このときの逸話として、跡継ぎのいなかった小早川隆景が、同じく跡継ぎのいなかった本家の毛利輝元の養子にされないよう、秀吉に秀秋の受入れを申し入れたという逸話(陰徳太平記)が残っています。しかし実際には既に輝元には別の養子(一族の秀元)が決定していたため、隆景が自分の所領(九州)を引き継がせ、秀吉との関係を良好に保つために自ら決断したという見方もあります。文禄4年、秀秋と毛利輝元の養女との婚姻が行われました。輝元からその養女にあてた手紙の中に、秀秋は「利口者」であるとの記述があります。内々の手紙なので、輝元の秀秋に対する評価の一端が伺えます。一方で家臣と度々諍いを起こし、秀吉にたしなめられているので、若年による未熟さもあったと思われます。

小早川隆景肖像画、米山寺蔵 (licensed under Public Domain via Wikimedia Commons)

当時は、秀吉による朝鮮侵攻(文禄・慶長の役)が行われていたため、秀秋の領地(筑前国)は支援基地の一つになりました。秀秋自身も慶長の役では、16歳で初陣(総大将)として朝鮮に渡っています。ところが、1598年(慶長3年)に帰国すると、秀吉から越前国(現・福井県)への転封を言い渡されました。これは、秀秋の朝鮮での軽率な行動(自ら最前線に乗り込んだ)が原因とも言われますが、これも後の軍記物での記述です。実態としては、筑前国を秀吉の直轄領とし、侵攻の統制を強化するためだという見方もあります。代官として、石田三成が派遣されています。秀吉没後は、秀秋は筑前国の領主に復帰し、豊臣一門に準ずる大大名として、五大老に次ぐポジションと認識されていました(九条兼孝日記)。そのとき、関ケ原合戦が起こったのです。

豊臣秀吉肖像画、加納光信筆、高台寺蔵 (licensed under Public Domain via Wikimedia Commons)

もう一つの主役・松尾山城は、近江国(現・滋賀県)と美濃国(現・岐阜県)の国境に位置していて、1570年(元亀元年)には、近江の浅井長政が家臣をこの城に配置したという記録があります(偏照山文庫所蔵文書)。当時長政が、織田信長と対立するようになったからと思われます。その後、信長が近江国を支配下に置くと、一旦廃城となりました。1600年(慶長5年)8月10日、石田三成は大垣城に入城すると、城主・伊藤盛正に対して、松尾山城に新城を築くことを命じました。三成はそのとき、大垣城と岐阜城(8月23日に落城)を拠点に、東軍に攻勢をかけることを考えていました。そして、その後詰(後方支援)として南宮山に毛利勢を入れました。また、背後の松尾山城には毛利輝元が入るはずだったという説(中井均氏)や、そのまた奥の玉城(たまじょう)には豊臣秀頼が入ることを想定していたという説(千田嘉博氏)もあります。いずれにしろ、関ケ原合戦のときには、松尾山城は西軍の有力部隊が布陣するために整備されていたのです。

松尾山城跡に立つ小早川秀秋の幟

「問鉄砲」を含む従来説

関ヶ原合戦の従来説は、明治時代に陸軍参謀本部が作成した「日本戦史」をもって固まったと言われています。歴史の本に出てくる関ヶ原の布陣図も、「日本戦史」のものがベースになっているそうです。今回注目する視点から、従来説をご説明しますが、新説の広まりによって、従来説を補強する意見(笠谷和比古氏などによる)も出てきていますので、併せてご紹介します。

西軍は8月1日に伏見城を落城させましたが、小早川秀秋勢は、主力としてこの戦いに参加しました。その後は表向きは、西軍の一員として行動していました。西軍の主力は大垣城に籠城していましたが、小早川勢は近江国周辺を行軍していたとされています。実際に、秀秋が近江の寺(成菩提院)に出した禁制(兵士に対する禁止事項)が残されています。その一方で東軍側とも交渉していて、東軍に味方する密約も交わしていました。これについては、東軍の黒田長政・浅野幸長からの密書があります。その中では「北政所」の名前を出され、東軍に味方することが彼女に報いることだと説かれています(下記補足1)。

(補足1)(前略)あなた様がどこに居られようとも、この度の忠節が非常に大切です。二・三日中に家康公がご到着されますので、それ以前に決断しなければなりません。我ら二人は北政所様に引き続きお尽くししなければなりませんので、このように申し上げているのです。速やかなご返事をお待ちしております。(8月28日付黒田長政・浅野幸長小早川秀秋宛連署状。訳を「小早川隆景・秀秋」から引用)

成菩提院、米原市ホームページから引用

9月14日に家康が大垣近くの赤坂に着陣すると、得意の野戦に持ち込むために、西上して佐和山城を攻略作戦を立て、その情報をわざと西軍に流しました。その情報を得た西軍総大将の石田三成は、急きょ先回りをして夜中に関ヶ原に布陣しました。秀秋も三成指示により、それまでに松尾山城に着陣していました。これについては、三成が新しい事態に対処するために、自ら選択した結果とも考えられます。戦い直後に吉川広家が、西軍は佐和山に撤退しようとしていたと書状に書いているからです(下記補足2)。しかし東軍の動きが早くなったことで、関ヶ原で食い止めることになったのです。また、西軍諸将は、一旦関ヶ原より西側に移動したようですが、結果的に迎撃しやすい関ヶ原に、ほぼ従来説通りの布陣をしたと考えられます。江戸時代前期に既にそれに近い布陣図が作られているからです(下記補足3)。大谷吉継は、秀秋の裏切りを予測し、わざと松尾山近くの山中に布陣したとされていますが、最終的に関ヶ原の方に前進してきたようです。。

(補足2)これは佐和山へ二重引きをする心づもりであると見えました。(一重目が関ヶ原に当たる)(9月17日吉川広家自筆書状案、訳を「関ヶ原合戦を復元する」から引用)

(補足3)武家事記所収の布陣図(山鹿素行)

石田三成肖像画、東京大学史料編纂所蔵 (licensed under Public Domain via Wikimedia Commons)

戦いは、午前8時頃始まりましたが、午前中は一進一退で、西軍は善戦していました。しかし東軍と密約を交わしていた南宮山の吉川勢と、松尾山の小早川勢は動きませんでした。秀秋は東軍に寝返る約束もしていましたが、それもしていませんでした。業を煮やした家康は、小早川勢に対して発砲を命じ、狼狽した秀秋はついに西軍への攻撃を決心したのです。この開戦と、小早川参戦の時間差については、戦いに参加した島津義弘や島津家臣が証言しています(下記補足4)。また「問鉄砲」は否定されているということですが、それに近い話が伝えられています(備前老人物語)。松尾山の麓で鉄砲の音がしたので、秀秋が調べさせたところ、それは徳川方の誤射だったというのです(下記補足5)。それは実は抑制された警告射撃かもしれず、もしかしたら「問鉄砲」ストーリーの元になった可能性もあります。小早川勢は大軍(8千とも1万5千とも)だったので、一部は山麓に展開していて、このようなことに気づくこともあったのではないでしょうか。

(補足4)
慶長五年庚子九月十五日、美濃国関ヶ原において合戦あり。数時間、戦ったが未だ勝負を決せざるところ、筑前中納言(秀秋)が戦場で野心を起こしたため、味方は敗北し、伊吹山逃げ登った。(島津義弘「惟新公御自記」、訳を「関ヶ原合戦を復元する」から引用)
夜明けとともに東国衆が大谷吉継の陣地へ攻撃を開始しました。6,7回戦闘が繰り返されましたが、小早川秀秋隊が山から降りてきて側面を攻撃し、吉継の人数を一人も残さず討ち取ってしまいました。(神戸五兵衛覚書、訳を「関ヶ原の合戦はなかった」から引用)

(補足5)小早川軍が松尾山に布陣して東西両軍の戦いを観望していたときのこと、麓の方で自軍に向けた鉄砲の射撃音のするのが聞こえた。そこで小早川の使番は、秀秋の命を受け下山して調べようとした。ところが、そのとき徳川方の武士が下から上がってきて、これは誤射であり御懸念無用にと述べ、調査の必要はないと強く申し立てた。しかしその使番は、調査は主君からの命令であるとして、それに構わず現場の状況をあれこれ調べたところ、単なる誤射ではなくて、かなり複雑な事情がある行為であったようだ。(「備前老人物語」のエビソード、「論争 関ヶ原合戦」から引用)

徳川家康肖像画、加納探幽筆、大阪城天守閣蔵 (licensed under Public Domain via Wikimedia Commons)

小早川秀秋は裏切っていないとする説

次は、最近出ている新説(白峰旬氏などによる)から、秀秋と松尾山城に関係するものをご紹介します。まず合戦前の秀秋の所在ですが、実はあまりはっきりしていないのです。近江にいたというのは、秀秋の家老を務めていた稲葉家が江戸時代に幕府に提出して記録に基づいていると思われます(寛永諸家系図伝・寛政重修諸家譜)。そこには、小早川勢が9月14日、松尾山城にいた伊藤盛正を追い出して入城したともあります。それであれば、既に「裏切り」を決断していたように思えるのですが、この記録は稲葉家の徳川家への貢献を強調するよう編集されている可能性があるので、鵜呑みにはできません。一方、大垣城に籠城していたという記録もあります。東軍として浜松城にいた保科正光が、籠城中の武将として、秀秋の名前を挙げているのです(下記補足6)。いずれにしろ、東軍からの勧誘を受けていたのは確かですので、西軍と行動を共にしつつ、迷っていたのではないでしょうか。同盟のため、9月14日付で秀秋の家老宛に出された東軍の井伊直政・本多忠勝連名の起請文があったとされていますが、これも江戸時代の軍記物(関原軍記大成)に記載されているだけなので、確実とは言えません。

(補足6)昨日(28日)、東軍先手衆から何度も報告がきました。それによりますと、大柿城には、三成・秀家殿・秀秋殿・惟新・行長ら、そのほか豊臣馬廻衆の精鋭らが2万人ほどで立て籠もっています。(8月29日付黒河内長三宛保科正光書状、訳を「天下分け目の関ヶ原の合戦はなかった」から引用)

秀秋の家老だった稲葉正成肖像画、神奈川県立歴史博物館蔵 (licensed under Public Domain via Wikimedia Commons)

実は、秀秋が開戦時に松尾山城にいたことを示す確実な史料はないのです(白峰旬氏による)。しかし開戦直前の状況として先ほどの吉川広家の書状に「秀家の逆意がはっきりしたので、大谷吉継救援のため、西軍が山中(関ヶ原の西)に移動した」とあるのです(下記補足7)。これによれば、関ヶ原周辺に秀秋と吉継が既に布陣していたことになります。また、戦い直後に伊達政宗は、西軍は南宮山の毛利勢を支援(後詰)するため大垣城から陣を移したと言っています(下記補足8)。これらから考えると、関ヶ原合戦直前、赤坂にいた徳川家康が南宮山の毛利勢を攻めようとし、秀秋が寝返ったことも伝わったので、三成は大垣城から出る決断をしたのだと考えられます。そして南宮山にいた吉川広家は不利を悟り、家康に事実上の降伏をしたのでしょう。そのため東軍は、三成が率いる西軍主力を追って、関ヶ原に進出したのではないでしょうか。なお、西軍が布陣したのは、前述の通り、関ヶ原ではなく、その西の「山中」でした。三成にとっては、そのときその場で戦になるとは想定外だったかもしれません。

(補足7)筑中は早くも逆意を明らかにしました。それにつき、大垣の衆(三成ら)も(かの地(大垣)にいられなくなり)大刑少(吉継)の陣が気がかりとのことで、山中へ向かって引き揚げました。(9月17日吉川広家自筆書状案、訳を「関ヶ原合戦を復元する」から引用)

(補足8)大垣城への「助衆」(毛利勢)に対して合戦を仕掛けるため、家康が14日に赤坂近辺へ陣を進めたところ、大垣城に籠城していた衆が夜陰に紛れて美濃の「山中」というところへ打ち返して陣取りをした(9月晦日付家臣宛伊達政宗書状、訳を「歴史群像145号」から引用)

吉川広家肖像画、東京大学史料編纂蔵(licensed under Public Domain via Wikimedia Commons)

以上が正しければ、秀秋は合戦前日には、東軍への参加を表明したことになります。合戦当日の経緯ですが、西軍は従来説よりも短時間で敗北したと考えられます(下記補足9)。また、開戦時間も早朝ではなく(午前10時頃)、秀秋も当初から戦いに参加したとの記録があります(下記補足10)。開戦時刻については史料によって早朝から10時頃までまちまちですが、以下のようにも考えられます。関ヶ原一帯は当日霧が深く、西軍ではそこに大谷勢が進出していました。そこで東軍先鋒との戦いが早朝に起こり、霧が晴れた段階(10時頃)で、松尾山から降りてきた小早川勢が参戦し、大谷勢が全滅したのです。そして東軍と西軍主力の戦いが山中で始まり、短時間で決着したという流れです。というのは、家康がそのとき発した書状に両者(関ヶ原・山中)の使い分けが見られるからです(補足11・12)。

(補足9)家康方軍勢が山中に押し寄せて合戦に及び、即時に討ち果たした(9月17日付吉川広家自筆書状案、訳を「歴史群像145号」から引用)

(補足10)15日の巳の刻(午前10時頃)、関ヶ原で一戦及ぼうとして、石田三成・島津義弘・小西行長・宇喜多秀家が関ヶ原に移動した。東軍は井伊直政・福島正則を先鋒としてその他の部隊を後に続けて、西軍の陣地に攻め込んで戦いが始まった時、小早川秀秋・脇坂安治・小川祐忠・祐滋父子の4人が御味方して、裏切りをしたので、西軍は敗北した(9月17日付松平家乗宛石川康通・彦坂元正連署書状写(堀文書)、訳を「動乱の日本戦国史」から引用)

(補足11)今度関ヶ原御忠節之儀、誠感悦之至候(9月24日付小早川秀秋宛徳川家康書状)

(補足12)今十五日午前、於濃州山中及一戦、備前中納言・島津・小西・石治部人衆悉討捕候(9月15日付伊達政宗宛徳川家康書状)今月十五日の午の刻(正午頃)、美濃国の山中において一戦におよび、備前中納言(秀家)、島津(惟新)、小西(行長)、石治部(三成)の軍勢を悉く討ち取りました。(訳を「関ヶ原合戦を復元する」から引用)

徳川家康最後陣地

西軍が松尾山城攻めをしたとする説

前説においても、秀秋が関ヶ原合戦の最中に「裏切り」を決断したわけではないことがわかりますが、状況証拠の集まりで、明らかに合戦当日に最初から東軍側に立ち、西軍と対峙していたという形にはなっていません(戦とはそういうものかもしれませんが)。それを明確にしてくれるのが「関ヶ原合戦は西軍が、松尾山城に籠る秀秋を討とうしようとして発生した」という説です(高橋陽介氏による)。この説での秀秋の合戦前の行動は、前説とそれ程変わらないようにも思えますが、東軍側のつく意志は早く固めていたことでしょう。

松尾山城跡

前説と異なってくるのは、開戦直前の三成など西軍主力の状況です。この説では、前説で取り上げた吉川広家の同じ書状の解釈が異なり、西軍主力が秀秋のいる「山中」に攻め込み、大谷吉継が後を追いかけているとしているのです(下記補足13)。また、島津家臣の後年の記述によると、9月14日の大垣城の軍議中に注進が入り、秀秋が寝返ったことが判明したというのです。(下記補足14・15)つまり、三成たちは秀秋を討つために関ヶ原方面に向かったのです。

(補足13)宇喜多・島津・小西・石田らが山中へ攻め込んだため、秀秋の逆意は明らかになりました。そのため、大柿にいた者たちも、そこに留まっていることができなくなってしまいました。吉継は心細くなって、山中に向かって撤退していきました。きっとそのあと、佐和山まで撤退するつもりだったのだと思います。(9月17日付吉川広家自筆書状案、訳を「天下分け目の関ヶ原の合戦はなかった」から引用)

(補足14)「然に筑前中納言一揆被起_内府様方に被差出之由、九月十四日に大柿江相知れ申し候事、」(宮之原才兵衛書上)

(補足15)「ヶ様之御談合最中に、筑前中納言殿野心之よし注進候、」 (井上主膳覚書)

大谷吉継墓

三成が陣を布いたのは、従来説の「笹尾山」ではなく、藤下村の「自害が岡」という所でした(下記補足16)。島津家臣の後年の記述を検討すると、松尾山に対して、第一陣が宇喜多・小西、第二陣が島津、その東に石田という布陣になっていました。他の史料で「第一陣が石田、第二陣が島津」となっているものがありますが、それは、秀秋を救援するために駆け付けた東軍主力部隊からの見方です。大谷隊は後から来たために、一番東の関ヶ原に布陣することになりました。そのため、東軍先鋒と戦うことになり、結果的に小早川隊と挟み撃ちに遭い、一番最初に壊滅してしまったのです(上記補足4)。同じ史料でも全く違う局面を表わしていることになります。

(補足16)「治部少本陣は松尾山の下自害か岡と云所に陣す、所の者不吉也と云ふと云々、」(戸田氏鉄「戸田左門覚書」)

自害が岡

リンク、参考情報

関ヶ原の残党、石田世一の文学館
・「小早川隆景・秀秋/光成準治著」ミネルヴァ書房
・「シリーズ・実像に迫る005 小早川秀秋/黒田基樹著」戒光祥出版
・「東海の名城を歩く 岐阜編/中井均・内堀信雄編」吉川弘文館
・「新説戦乱の日本史/千田嘉博他著」SB新書
・「論争 関ヶ原合戦/笠谷和比古著」新潮選書
・「関ヶ原合戦を復元する/水野伍貴著」星海社新書
・「歴史群像145号 関ヶ原合戦の真実/白峰旬著」学研
・「新視点 関ヶ原合戦/白峰旬著」平凡社
・「関ヶ原合戦全史 1582-1615/渡邊大門」草思社
・「天下分け目の関ヶ原の合戦はなかった/乃至政彦・高橋陽介著」河出書房新社
・「関ヶ原新説(西軍は松尾山を攻撃するために関ヶ原へ向かったとする説)に基づく石田三成藤下本陣比定地「自害峰」遺構に関する調査報告」高橋陽介氏・石田章氏論文
・「動乱の日本戦国史/呉座勇一著」朝日新書

「松尾山城その2」に続きます。

今回の内容を趣向を変えて、Youtube にも投稿しました。よろしかったらご覧ください。

20.Sakura Castle Part1 (draft)

Sakura Castle was located at the current Sakkura City of Chiba Prefecture. The castle was built as the home of the Sakura Domain during the Edo Period, which is the origin of the city. The areas around the city had many other castles until the Sengoku Period and some of which were very important.

Location and History

Sakura Castle was located at the current Sakura City of Chiba Prefecture. The castle was built as the home of the Sakura Domain during the Edo Period, which is the origin of the city. The areas around the city had many other castles until the Sengoku Period and some of which were very important. For example, there was Usui Castle in the western part of the city, where the battle of Usui Castle happened back in 1566. Kenshin Uesugi, who tried to rule the whole Kanto Region, attacked the castle but failed. There was also Motosakura Castle in the eastern part, which was the home of the Chiba Clan. Usui Castle was a branch of the clan. Cuttently, this castle is called “Motosakura” but back then, it was called “Sakura Castle”. So therefore, Sakura Castle was the former name of Motosakura Castle. This article will explain the formative years of Sakura Castle including the formation of Motosakura Castle, which should make it easier for people to better understand the history.

The ruins of Usui Castle, Notice the wooden log steps covered in soil
The ruins of Motosakura Castle, Notice the icon on the wooden shields.  This is the family crest of the Chiba Clan

Formative Years of Sakura Castle

The Chiba Clan had owned Shimosa Province, which was the northern part of Chiba Prefecture, since the end of the ancient times. The most famous person of the clan would be Tsunetane Chiba who supported the launch of the Kamakura Shogunate at the end of the 12th Century. Their home, Inohana Castle, was located at the current Chiba City for a long time. However, the castle was destroyed when many battles occurred in the 15th Century during the Sengoku Period. The clan decided to rebuild their new home in another location, which would be called Motosakura Castle. The castle was on the Shimosa plateau and was surrounded by Inbanuma Lake and other waterlogged areas. Its location was much more fortified than before and more convenient for water transportation. The lake was also much larger than now, where people could easily access Kasumigaura Lake and other great rivers. The wide water area was even called Katori-no-umi, which means the Katori inland sea.

The statue of Tsunetane Chiba, exhibited by Chiba City Folk Museum
The whole map of Motosakura Castle, from the signboard at the site

The situation changed during the 16th Century. The Hojo Clan was invading the Kanto Region from the west. On the other hand, the Satomi Clan also got the power from the south (Boso peninsula). The Chiba Clan wondered what to do and they eventually allied with the Hojo Clan. That’s why Kenshin Uesugi, who would help the Satomi Clan, decided to attack Usui Castle, a branch of the Chiba Clan. The victory of the clan was partially due to the Hojo Clan’s help. As a result, the Hojo became more effective to the Chiba Clan. As for the home of the clan, Chikatane Chiba, who was the lord of the clan before the battle, originally planned to move his home from Motosakura to another. The new land for his new home later became Sakura Castle, which was called Kashima Castle then. Mysteriously, he died in 1533, which ultimately canceled his plans of moving the castle.

The location of the castle, Notice the smaller Inbanuma Lake on the left next to Usui Castle. This important river used to span much larger that what the current map is showing. It used to be part of a much larger body of water.

The portrait of Kenshin Uesugi, owned by the Uesugi Shrine (licensed under Public Domain via Wikimedia Commons)
The portrait of Chikatane Chiba, owned by the Kubo Shrine (licensed under Public Domain via Wikimedia Commons)

The Hojo Clan interfered in the internal affairs of the Chiba Clan at the end of the 16th Century. For instance, Ujimasa Hojo married his daughter to Kunitane Chiba, the lord of the clan. The Hojo Clan allowed Kunitane to resume the construction of Kashima Castle but failed to do so because the lord was killed again. Ujimasa next married his son to Kunitane’s daughter, in order to be the successor of the clan. It was said that Kashima Castle was finally finished for the new home of the couple.

The portrait of Ujimasa Hojo, owned by Odawara Castle (licensed under Public Domain via Wikimedia Commons)

However, it is difficult to confirm these records are the fact, as Sakura Castle was built on the old Kashima Castle. the few discovered old dry moats at the site prove that they were at least trying to build the castle there. So, why did the Chiba and Hojo Clans want to move there again and again? One of the reasons would be that the land for the new castle was much larger than the old one. For the Hojo Clan, another possible reason may have been to protect their territories from the invasion of Hideyoshi Toyotomi from the west. The plateau, which the new castle was built, had steep slopes and was surrounded by rivers towards the direction. That would be very defensive against the invasion. However, the Chiba Clan was eventually fired by Hideyoshi, after their master, the Hojo Clan was defeated at the battle of Odawara Castle in 1590.

The current Sakura Castle
The current Odawara Castle

51.Azuchi Castle Part1

Azuchi Castle, which had many unique characters, suddenly appeared and disappeared in a short amount of time like its master, Nobunaga. As a result, it has a lot of mysteries which attract us. This article will focus on 5 items of the mysteries, which people often dispute about.

Azuchi Castle was, needless to say, known for the final and most popular home of Nobunaga Oda. Other than that, he created a typical style of Japanese castles, including the main tower, turrets, and white walls on top of the stone walls, which are guarded by defensive gates and are surrounded by water moats. The style was passed down from one generation to the next by other great Japanese lords. That’s why we still think it as the most typical Japanese castles’ style. Therefore, Azuchi castle was the inspiration for many other castles that came after it.

The portrait of Nobunaga Oda, attributed to Soshu Kano, owned by Chokoji Temple, in the late 16th century (licensed under Public Domain via Wikimedia Commons)

However, the castle had a very short life for its impact. The construction of the castle launched in 1576. Nobunaga started to live in its main tower three years later. Its completion was done in September of 1581 (according to the luna calendar), just 9 months before Nobunaga’s death during the Honnoji Incident in Kyoto on the 3rd of June the following year. The main tower of the castle was burned down around the 15th of June for some unknown reasons. The Oda’s relatives still used the remaining parts of the castle for a while. Atter that, the castle was eventually abandoned in 1585 because their new home, which was called Hachimanyama Castle, was completed.

The ruins of Hachimanyama Castle

As you saw, the castle, which had many unique characters, suddenly appeared and disappeared in a short amount of time like its master, Nobunaga. As a result, it has a lot of mysteries which attract us. For example, its own name “Azuchi” is one of them. A record of the Hosokawa Clan says that Nobunaga changed the name of the land to Azuchi. However, the record doesn’t say why. Some speculate the name came from Kyoto’s nickname “Heian-rakudo” which borrows the two Chinese characters of Azuchi (安土). The original Chinese characters of Heian-rakudo is as followed: 平安楽土. They think Nobunaga wanted the castle to be the new capital of Japan. The speculation is not very plausible because other experts argue that other speculations are more plausible.

Azuchi Mountain

This article will focus on 5 items of the mysteries, which people often dispute about. I will also compare Theory A with Theory B for each item by summarizing the opinions about each one. Theory A will mainly consist of conventional wisdom from the officials, historians, and experts. Theory B, on the other hand, will focus on the opinions of Mr. Senda who is a famous castle archaeologist and from me (in the last part).

Location and History (Mystery Showdown)

Mystery of the Straight Main Route to the Mountain

Introduction

A surprising thing was discovered in the ruins of Azuchi Castle during the excavations since 1989 by Shiga Prefecture. Castles on mountains during the Sengoku Period usually had zigzagged routes to the top and had defensive walls, gates and turrets on the way to the top. Azuchi Castle Ruins had had stone walls on the way of the main route, which looked like a typical mountain castle at that time. However, the stone walls were built by Sokenji Temple at Azuchi Mountain during the Edo Period, abd not the Sengoku Period. The excavation team removed the stone walls and discovered that there was the original straight main route to the mountain, which is approximately 180m long. It also found the ruins of residential areas maybe for the senior vassals along the route, such as “Hideyoshi Hashiba (then later Hideyoshi Toyotomi who would be the ruler of Japan). In addition, four gate ruins were found around the entrance of the route. Three of the four gates had a simple design, called “Hira-koguchi”, where visitors (and possibly enemies) could have passed through easily. I wonder Why the straight main route was built instead of the zigzagged route which is typical of defensive castles during the Sengoku Period?

The diorama of the stone walls on the main route before it was removed, exhibited by Azuchi Castle Archaeological Museum
The current main route of Azuchi Castle
The ruins of the residence of Hideyoshi Hashiba

Theory A

One theory suggests this route was used only for special visitors in special cases. It was particularly considered as the route for the emperor’s royal visit to Azuchi Castle though it never happened. That’s why the route was built straight for the convenience of the visitors. The straight layout might also have been emulated to look like the central street of Kyoto. In addition, there are no records of this route because it was rarely used. The three simple gates around the route entrance must have also been built only for these visits. The layouts were very similar to that of the imperial palace at that time. The gates were used depending on the visitors’ classes. The ruins of the residential areas along the route might have been used as the facilities for the visitors. According to the imaginary drawing through the use of CG of the main route, the great main tower of the castle stands over there (refer to the third picture at the bottom). The visitors on the route would feel the power of the castle’s master, Nobunaga Oda

The ruins of the main gate
The diorama of Azuchi Castle, exhibited by Azuchi Castle Archaeological Museum
The imaginary drawing of the main route of Azuchi Castle, exhibited by Gifu Castle

Theory B

The next theory was the main route was built not only for the royal visit, but also for the residential areas, as I mentioned earlier. In fact, Nobunaga had built the similar straight main route in Komakiyama Castle on Komakiyama Mountain, which was his home earlier on. The residential areas of his senior vassals were constructed along the route, too. The route was straight until the midway point of the slope of the mountain but the route above had zigzagged patterns for defensive purposes. This had been done when Nobunaga was young, so he never met the emperor. Azuchi Castle had the same system as Komakiyama Castle. The route to the top zigzags after 180m. Several defensive gates were also built on the way to the upper part. Why didn’t Nobunaga make all the routes straight if he wanted them to use only for the royal visits? The reason for the three simple gates were designed to classify Nobunaga’s retainers when they went to the castle. In addition, the masters of the residential areas of Azuchi Castle were very busy and had their own territories in other locations. As a result, the areas were usually vacant, which wouldn’t appear on records.

The ruins of Komakiyama Castle
The main route of Komakiyama Castle
The zigzagged route of Komakiyama Castle just after the straight route

Mystery of the Main Hall

Introduction

The excavation team also researched the top area of Azuchi Mountain, which includes the main enclosure. They found another answer. The team discovered that the stone foundations of the main hall on the enclosure have wider intervals than the typical halls at that time. After some studies, it was found that the layout of the stone foundations of Azuchi Castle Hall is very similar to that of Seiryoden Hall in the imperial palace during the Edo Period. Shincho-koki, which is the most reliable biography of Nobunaga, stated that Azuchi Castle had room for the royal visit or the emperor’s stay. A noble’s diary also says that the emperor would go to Azuchi. What did the main enclosure of Azuchi Castle really look like?

The current main enclosure of Azuchi Castle

Theory A

One plausible theory suggests there must have been the main hall for the emperor on the main enclosure. Nobunaga might have thought he would move the emperor and the capital of Japan from Kyoto to Azuchi. Before the construction of Azuchi Castle, Nobunaga retired as the lord of the Oda Clan. He also resigned from all his positions in the imperial court until the completion of the castle. Nobunaga might have wanted to be the person who surpasses all the positions of Samurai and the imperial court. He actually gave his castle in Kyoto to the current prince. He also adopted the prince’s son. These facts might indicate that Nobunaga would invite one of them to Azuchi as the new emperor. If the new emperor lived in the main hall of the main enclosure, Nobunaga could look down on him from the much higher main tower. That would symbolize Nobunaga was just like the most powerful monarch of Japan.

The portrait of Prince Sanehito, owned by Sennyuji Temple, (licensed under Public Domain via Wikimedia Commons)

Theory B

An alternative theory suggests the main hall must have been the government offices. Nobunaga usually lived in the main tower and the second enclosure, with his family where other people were rarely allowed to enter. The other third enclosure on the mountain was used as the reception hall. Therefore, if the main enclosure was used just for the emperor, there would be no place for the government to stay in. According to architects, it is impossible to determine what was built using only stone foundations. The Shincho-koki biography also states that there was another hall, called “Nanden” (which means “south hall”) in the enclosure. It was thought that Nobunaga usually met his retainers there. “The royal visit room”, written in the biography, also states that there was probably part of the hall or another small hall. As for Nobunaga’s position, he might have destined to become the next shogun, which was the traditional position for the new shogunate, according to a historian’s study.

The center of the diorama above, showing the second enclosure, the main tower ruins, the main enclosure, and the third enclosure (from the left to the right), exhibited by Azuchi Castle Archaeological Museum

Mystery of the Main Tower

Introduction

The main tower of Azuchi Castle is one of the examples of the first proper high buildings for Japanese castles at that time. It was said that Nobunaga was the only person who lived in a main tower according to records. The tower must have had a spiritual aura and authoritative presence. According to Gyuichi Ota who was the author of the Shincho-koki biography and Luis Frois, a missionary who visited Japan at that time, it was about 32m tall (41m including the tower base) composed 5 levels (6 floors and 1 basement). The tower was very colorful. Especially, the 5th floor was a red octagon shape with Buddhist paintings on the inside walls. The top 6th floor was a golden square shape with Chinese saints’ painted on the inside walls. There are a lot of remaining stone foundations to the base, but they just lack the central one, which comes from the original conditions. What did the main tower actually look like?

The stone foundations of the tower base, which lacks the central one
The miniature model of the 5th floor, exhibited by Azuchi Castle Museum
The miniature model of the 6th floor, exhibited by Azuchi Castle Museum

Theory A

A popular theory suggests there is a drawing which shows the design of the tower, called “Tenshu-sashizu” (which means “the design of the tower”). It was recorded and passed down by a magistrate family of the Kaga Domain. It doesn’t say it is the design of Azuchi Castle tower, however, it matches the records mentioned above and the on-site situations. Dr. Akira Naito made a restoration plan using the drawing, which is wildly accepted. According to the plan, the tower had an atrium structure, and a pagoda on the center of the base without the stone foundation. Experts speculate that the pagoda would indicate the appearance from the ground, written in the Lotus Sutra. You can see the 1/20 scale model based on the plan in Azuchi Castle Museum. You can also see the real life model of the 5th and 6th floors of the tower in Nobunaga no Yakata Museum. The tower was vewed as a heaven for Nobunaga who would reign over the pagoda as the only living god.

The miniature model of the main tower, exhibited by Azuchi Castle Museum
The atrium structure and the pagoda in the model
A figure of Nobunaga siting on the 5th floor

Theory B

Others have argued the plan based on the Tenshu-sashizu drawing. They say that it is impossible that the characteristic atrium structure was not recorded. For this reason, there is another restoration plan which doesn’t the atrium. Furthermore, the most controversial problem is that if you rebuild the main tower just as Gyuichi said, the tower will have to hang over the existing base. Dr. Yoshihiro Senda has an alternative theory however. He says that the tower would be able to be supported by Kake-zukuri method. This method involves building the foundation by combining many columns and horizontal beams like lattices on rocks or the ground. Buildings using this method can been seen in some old shrines and temples such as Kiyomizu-dera Temple in Kyoto. It has also been seen in some castles like Himeji and Fukuyama. Dr. Senda points out the traces of stone foundation were found beside the base, which could indicate the Kake-zukuri method was used. In addition, the decisive evidence could be found in the future. Nobunaga sent the screen of illustration of Azuchi Castle, called “Azuchi-san-zu-byobu” to the Pope. The screen was once exhibited in the Vatican Palace but disappeared mysteriously. Officials from Shiga Prefecture is currently seeking for it in Italy. If it is found, it could be the discovery of the century.

The building based on the plan without the atrium (licensed by D-one via Wikimedia Commons)
An example of castle buildings using the Kake-zukuri method, at Fukuyama Castle, quoted from Fukuyama Castle Museum Website
The area beside the tower base, where the traces of stone foundation were found
The imaginary drawing of the “Azuchi-san-zu-byobu” screen

Mystery of Sokenji Temple

Introduction

Nobunaga founded Sokenji Temple inside Azuchi Castle. It is large for a castle. The materials of the temple were not new but were collected from older temples. This temple currently worships Nobunaga. However, curious to say, the temple officially says it was founded by a priest after Nobunaga died. According to Gyuichi’s records, there was a stone, named Bonsan, in the main tower. However, the stone was moved to the temple, according to Luis Frois. The temple was located at the middle point between the center of the castle and the side entrance. This point was important for protecting the castle, where defensive systems could have been built. So, why did Nobunaga build the temple instead of the systems?

The remaining Nio-mon Gate of Sokenji Temple
The remaining three-level tower of Sokenji Temple
The current side entrance

Theory A

Frois also said that Nobunaga founded the temple in order to make people worship him there. The Bonsan stone was the icon of Nobunaga. Frois described that Nobunaga also built a public noticeboard which states people should go to the temple and worship him on his birthday. As a matter of fact, Nobunaga thought his birthday (the 11th of May according to the luna calendar) was like the birthday of the western people. For example, he moved to the main tower on that day, not during lucky days where most Japanese people believed in. The conclusion is that Nobunaga made the important spot as his holy place of the temple.

The grave of Nobunaga at the second enclosure
There is a stone on the grave, which looks like Bonsan

Theory B

In fact, it was not unusual that castles had temples inside them. For instance, Kannonji Castle near Azuchi had Kannon-seji Temple. Takakage Kobayakawa, who was a great warlord in the Chugoku Region, built Kyoshinji Temple in his Ni-Takayama Castle. During the Muromachi and Sengoku Periods, the Samurai ceremonies consisted of two phases. The first one was to confirm the master-servant relationship at Shuden places. The second was to communicate with each other at Kaisho places. In the case of Azuchi Castle, the center of the castle was clearly equivalent to a Shuden place. Meanwhile, Sokenji Temple must have been used as a Kaisho place. For example, when Nobunaga invited his ally, Ieyasu Tokugawa to Azuchi Castle, a Noh play (similar to Kabuki play) was held there. In addition, there are no records about people worshiping Nobunaga at the Japanese side.

The diorama of Kannonji Castle, exhibited by Azuchi Castle Archaeological Museum
Kannon-seji Temple (licensed by Jnn via Wikipedia Commons)
The ruins of Ni-Takayama Castle
The ruins of the Kyoshinji Temple

Mystery of the Main Tower burning down

Introduction

The center of Azuchi Castle, including the main tower, was burned down around the 15th of June in 1582 (according to the luna calendar), just after the Honnoji Incident on the 2nd of June. The following list are the relatives who were involved in using the castle and also the prime suspects who might have burned it down.

・Katahide Gamo: He was at Azuchi Castle on behalf of Nobunaga when the incident happened. However, he left the castle with Nobunaga’s family on the 3rd of June after he heard about the incident.
・Mitsuhide Akechi: He entered the castle on the 5th of June after he killed Nobunaga during the incident. He then gave the treasures of the castle to his retainers and moved to his original home of Sakamoto Castle.
・Hidemitsu Akechi: He was Mitsuhide’s retainer and held the castle instead of Mitsuhide. He left the castle on the 14th of June after he heard about his master being beaten by Hideyoshi Hashiba on the 13th. Taikoki, which is one of Hideyoshi’s biographies, says Hidemitsu was responsible for setting the castle on fire.
・Nobukatsu Oda: He was Nobunaga’s son, and he entered the castle on the 15th of June. According to Luis Frois, it was Nobukatsu who burned the castle down.

The castle might have burned down accidentally or by night thieves. However, if you must speculate one person from the list, who was the biggest suspect?

The stone foundations of the main tower base

Theory A

Nobukatsu must be the suspect as Frois said. Hidemitsu had an alibi that he was at Sakamoto Castle on that day. The Taikoki biography is only adds to the blames of the Akechi Clan. Frois also said that Nobukatsu did it for no reasons because he was unwise. Before the incident, he selfishly attacked Iga Province, failed to do so, and was yelled at by Nobunaga. After the incident, he battled against Hideyoshi, together with Ieyasu Tokugawa. However, he eventually made peace with Hideyoshi who dangled a carrot in front of him, without Ieyasu’s permission. Finally, he was fired by Hideyoshi who became the ruler after the battle of Odawara Castle. He rejected the change of his territory, ordered by Hideyoshi, though Ieyasu accepted it. Nobukatsu was not able to understand the situations properly. He was so incompetent that he could impulsively destroy the legacy of his father who was also angry at him.

The portrait of Nobukatsu Oda, owned by Sokenji Temple (licensed under Public Domain via Wikimedia Commons)

Theory B

This theory is believed in. Nobukatsu must be the suspect, too. However, he was not so incompetent that he did it for a good reason. When he attacked Iga Province, he was the independent lord of the Kitabatake Clan, so he could decide it. Nobunaga had adopted Nobukatsu to the clan as the next successor. He was still the lord of the Kitabatake Clan when he allied with Ieyasu. Hideyoshi mostly captured the territory of the clan (Ise Province) because Ieyasu was so strong. Nobukatsu had to compromise with Hideyoshi before his territory would be occupied. After that, he tried to mediate between Hideyoshi and Ieyasu. He also worked hard in the battle of Odawara Castle for Hideyoshi’s unification of Japan. Therefore, it might not be sensible for Nobukatsu to be fired completely even though he rejected Hideyoshi’s command. This might have been Hideyoshi’s strategy which attempted his prefered territory plan. After the Honnoji Incident, Nobukatsu wanted to be the lord of the Oda Clan, not just that of Kitabatake Clan. However, his brother, Notbutaka also wanted it. Nobukatsu might have burned the main tower down intentionally in order to prevent Nobutaka and other senior vassals from disturbing him.

The portrait of Nobutaka Oda, (licensed under Public Domain via Wikimedia Commons)

To be continued in “Azuchi Castle Part2”