Ryoto Tetsuritsu

In the latter half of the Kamakura period, the principle of imperial succession was that the line of Emperor Gofukakusa (Jimyoin line) and the line of Emperor Kameyama (Daikakuji line) would take the throne alternately. After the death of Emperor Gosaga (1272), a dispute arose between his two sons, Emperor Gofukakusa and Emperor Kameyama, over which line would succeed to the throne. This, combined with a dispute over the imperial estates, led to the Imperial Family splitting into two. The Kamakura Shogunate, which had been a major voice in the issue of Imperial succession since the Jōkyū War (1221), placed importance on the balance of power between the two lines, and when Emperor Kameyama's son Prince Yohito ascended to the throne (Emperor Go-Uda), with the mediation of the regent Hojo Tokimune, Prince Hirohito of the Jimyōin line (Emperor Fushimi) was appointed Crown Prince, which marked the beginning of the alternation of the two lines. However, this principle was not clearly stipulated, and conflicts over the Imperial succession continued even afterwards, and the conflict between the two lines gradually deepened due to disputes over Imperial estates such as the Muromachi-in estate. After the death of Emperor Go-Nijo of the Daikakuji line (1308), Prince Tomohito, the younger brother of the retired Emperor Go-Fushimi of the Jimyoin line, ascended to the throne (Emperor Hanazono), and Emperor Go-Nijo's younger brother Prince Takaharu (Emperor Godaigo) became crown prince. At this time, it was decided that the imperial throne of the Jimyoin line should in future be passed on to the Go-Fushimi line, and that of the Daikakuji line should be passed on to the Go-Nijo line. This created the possibility that the Jimyoin line would split again into the Go-Fushimi and Hanazono lines, and the Daikakuji line would split again into the Go-Nijo and Go-Daigo lines. Worried about this situation and unwilling to become embroiled in the conflict between the two imperial lines, the shogunate sent an envoy to Tokyo in 1317 (Bunpo 1) to encourage the two lines to discuss and determine the rules for imperial succession (Bunpo Peace Treaty). However, the discussions were difficult, and the compromise proposal presented by the shogunate, which was based on a ten-year rotation of the two lines, did not reach an agreement on the details, and without a clear resolution, Emperor Hanazono abdicated the following year in favor of Prince Takaharu, at the shogunate's request. Three years later, Emperor Go-Daigo regained control of his own government and took active political action, which eventually caused friction with the shogunate. Meanwhile, the Jimyoin line was gradually drawing closer to the shogunate. When Emperor Go-Daigo was captured in the Genkō Incident (1331), Emperor Go-Fushimi's son, Prince Tokihito, was supported by the Rokuhara Tandai and ascended to the throne (Emperor Kogon), and Emperor Kogon abdicated when the Kenmu Restoration government was established, but when the Kenmu government collapsed due to the defection of Ashikaga Takauji, the Jimyōin line was supported by the Ashikaga clan (Northern Court) and came into complete conflict with the Daikakuji line (Southern Court), and the conflict between the two lines shifted to that between the Northern and Southern Courts. When the two courts were unified in 1392 (Meitoku 3, Genchū 9), the condition was once again that the two lines be alternated in succession, but in reality this condition was not observed and only the Jimyōin line succeeded to the throne.

[Eiji Nitta]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

鎌倉時代後半、後深草(ごふかくさ)天皇系（持明院(じみょういん)統）と亀山(かめやま)天皇系（大覚寺(だいかくじ)統）の両統から交互に皇位につくとされた皇位継承の原則。後嵯峨(ごさが)法皇の死（1272）後、法皇の2子後深草上皇と亀山天皇との間に、いずれの系統が皇位を継承するかについての対立が生じ、これに皇室領荘園(しょうえん)をめぐる対立も加わって天皇家は二つに分裂した。承久(じょうきゅう)の乱（1221）以降皇位継承問題に干渉し、大きな発言力をもっていた鎌倉幕府は、両統の勢力の均衡を重視し、亀山天皇の皇子世仁(よひと)親王が践祚(せんそ)（後宇多(ごうだ)天皇）した際、執権北条時宗(ときむね)の斡旋(あっせん)で持明院統の煕仁(ひろひと)親王（伏見(ふしみ)天皇）を皇太子と定めたが、これが両統迭立の端緒となった。しかし、この原則は明確に規定されたものではなく、その後も皇位継承をめぐって対立が続いたうえ、室町院領などの皇室領荘園をめぐる争いなどから、両統の対立はしだいに深まっていった。大覚寺統の後二条(ごにじょう)天皇の死（1308）後、持明院統の後伏見(ごふしみ)上皇の弟富仁(とみひと)親王が践祚（花園(はなぞの)天皇）し、後二条天皇の弟尊治(たかはる)親王（後醍醐(ごだいご)天皇）が皇太子となったが、このとき、持明院統の皇位は後伏見系に、大覚寺統の皇位は後二条系にそれぞれ将来は伝えられるべきことが定められ、そのため持明院統が後伏見系と花園系に、大覚寺統が後二条系と後醍醐系にそれぞれ再分裂する可能性が生じた。こうした事態を憂慮するとともに両統の抗争に巻き込まれることを嫌った幕府は、1317年（文保1）に使者を上京させて両統の協議による皇位継承ルールの画定を促した（文保(ぶんぽう)の和談）。しかし協議は難航し、幕府から提出された10年交代の両統迭立を軸とする妥協案も、細部について合意をみず、明確な決着がつかぬままに翌年花園天皇は幕府の意を受けて尊治親王に譲位した。後醍醐天皇は3年後に親政を実現し、積極的な政治行動を展開して、やがて幕府との間に軋轢(あつれき)を生じた。一方この間に持明院統はしだいに幕府に接近していった。元弘(げんこう)の変（1331）で後醍醐天皇が捕らえられると、後伏見天皇の皇子量仁(ときひと)親王が六波羅探題(ろくはらたんだい)に擁立されて践祚（光厳(こうごん)天皇）し、光厳天皇は建武(けんむ)新政政府の成立によって退位したが、やがて足利尊氏(あしかがたかうじ)の離反で建武政府が倒壊すると、持明院統は足利氏に擁立され（北朝）、大覚寺統（南朝）と完全に対立するに至り、両統の対立は南北両朝の対立に移行した。1392年（明徳3・元中9）の両朝合一に際しては、ふたたび両統迭立とすることが条件とされたが、実際にはこの条件は守られず、持明院統のみが皇位を継承した。

［新田英治］

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例