著者

佐伯 真一

出版者

国立歴史民俗博物館

雑誌

国立歴史民俗博物館研究報告 = Bulletin of the National Museum of Japanese History (ISSN:02867400)

巻号頁・発行日

vol.182, pp.7-28, 2014-01

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「軍神」という概念について考える。「軍神」という言葉の用例としては、『梁塵秘抄』に見えるものが古く、次いで『平家物語』などの軍記物語に若干の例がある。中世後期には、兵法書の類に多くの例が見られる。そこで、従来、軍記物語に見える「軍神」と、『梁塵秘抄』に見える「軍神」、兵法書の類に見える「軍神」を、基本的に同じ範疇の中で捉えようとしてきたように思われるが、この三者は内容的に重なり合うことが少なく、一旦切り離して、別のものとして扱うところから考察を始める方がよさそうに見える。まず、軍記物語の「軍神」について。『平家物語』では数例見られ、諸本に異同があるが、概ね、合戦で敵の首を取ることを「軍神にまつる」という表現を中心としたものである。また、『保元物語』金刀比羅本や『太平記』、慈光寺本『承久記』などにも類似の例が見られる。首を取ることを「軍神にまつる」と表現するのは、武士たちがかつて実際に首を生贄に供えていたことに由来すると指摘されており、実際、そうした実感に即したものである可能性は強いが、首を祀る儀礼の実態は不明であり、「軍神」として特定の神格を祀る様子は窺えない。また、『梁塵秘抄』に「関より東の軍神、鹿島香取諏訪の宮…」などと歌われる「軍神」は、軍事的・武的性格を帯びた神々を列挙したものだろうが、各々の神がなぜ「軍神」とされるのかは、不明な点も多い。ともあれ、それらの神々が、近在以外の武士一般に、戦場で「軍神」として祀られたかどうかは疑わしい。こうした「軍神」は、軍記物語に描かれるような、合戦現場で首を取って祀る対象となる「軍神」とは異なるものと考えられる。次に、鎌倉時代成立と見られる『兵法秘術一巻書』をはじめ、いわゆる兵法書には、「軍神」がしばしば登場する。その「軍神」記述の最も中心となるのは軍神勧請の記述だが、それは『出陣次第』などに共通すると同時に、兵法書に限らず、たとえば『鴉鷺物語』などにも引用されている。だが、そこには軍記物語に見られたような、敵の首を「軍神」に祀るという記述はあまり見られない(皆無ではないことは後述)。また、兵法書などで祈願対象とされる神名は、空想的なものも含めて非常に雑多で、摩利支天などをはじめ、さまざまな神仏が挙げられる。そこには「九万八千の軍神」といった表現もしばしば登場するのだが、にもかかわらず、その中に、『梁塵秘抄』に歌われたような、鹿島・香取・諏訪といった日本古来の在地の「軍神」はほとんど登場しない。伊勢貞丈『軍神問答』は、兵法書的な世界に登場する「九万八千軍神」といった説や、摩利支天などの神仏を「軍神」として祀ることを否定して、「日本の軍神」としては「大己貴命、武甕槌命、経津主命」を挙げる。『梁塵秘抄』の挙げる鹿島・香取といった「軍神」認識に近い。貞丈の記述から逆説的に明らかになることは、中世の武士たちの「軍神」信仰が、『梁塵秘抄』と伊勢貞丈を結ぶような日本在来の正統的な神祇信仰ではなく、荒神信仰などを含む雑多な信仰だったことである。それは、おそらく、密教ないし修験の信仰や陰陽道などが複雑な習合を遂げ、合戦における勝利という武士の切実な要求に応じて、民間の宗教者が種々の呪術的信仰を生み出したものであると捉えられよう。さて、軍記物語に見える「軍神」と、兵法書の類に見えるそれとは別のものであると述べてきたが、仮名本『曽我物語』に見える「九万八千の軍神の血まつり」という言葉は、両者をつなぐものとして注目される。兵法書においても、『訓閲集』には巻十「首祭りの法」があり、そこでは「軍神へ首を祭る」儀礼が記されている。これらは数少ないながら、軍記物語に描かれた「軍神」の後継者ともいえようか。こうした「血祭り」の実態は未詳だが、そこで、中国古典との関連を考える必要に逢着する。言葉の上では、とりあえず漢語「血祭」(ケッサイ)との関連を考える必要があり、これはおそらく日本の「血祭り」とは関連の薄いものと思われるものの、『後漢書』などに見られる、人を殺してその血を鼓に塗るという、「釁鼓」(キンコ)には、日本の「血祭り」との類似性を考える事も可能だろう。軍記物語に見える、首をまつる「軍神」が、神に生贄を供える感覚に基づく言葉であるかどうかといった問題は、そうした言葉の広がりや兵法書の類の精査、さらには東アジア全体における同様の事例の検討などをふまえて、今後考察されねばならないのではないか。This paper examines the term ikusagami, meaning god of war. An early example of the use of ikusagami is found in the collection of folk songs, Songs to Make the Dust Dance, later followed by examples in a number of war chronicles such as the Tale of the Heike. In the later medieval period, the term can often be found in books on military tactics. Previously, it appears that these three ikusagami found in the various war chronicles, in the Songs to Make the Dust Dance, and in the books on military tactics have all been basically classified in the same category. These three different expressions of ikusagami, however, rarely overlap each other in terms of their meaning, and a good approach would be to first consider them as independent entities, and then to explore and consider their differences.Firstly, the ikusagami of the war chronicles is examined. In the Tale of the Heike several examples are found, and although there are differences among the various versions of the tale, in general an expression "offer to ikusagami" is mainly used; in this context this means to take the head of an enemy in battle. Similar examples can be seen in the Kotohira texts of the Tale of Hogen, the Record of Great Peace, and the Jikoji texts of the Jokyu-ki (Chronicle of Jokyu) . It is indicated that this expression meaning to take a head is derived from a custom where warriors would make an offering of a head as a sacrifice, and in fact, it is highly likely that the expression is based on this practice; however, the actual ritual of offering heads is unclear, and the possibility of worshipping a specific god as an individual ikusagami cannot be inferred.In the Songs to Make the Dust Dance, we find the lines "ikusagami ( these gods of war) live east of the barrier, Kashima-jingu Shrine, Katori-jingu Shrine, Suwa no Miya Shrine…," which is probably a list of gods with military or martial characteristics; however, there are many unclear points as to why each god is referred to as an ikusagami. In any case, it is doubtful whether these gods were worshiped as ikusagami by the common warrior on the battlefield in other rural areas. It can be considered that these kinds of ikusagami are different from the ikusagami depicted in the war chronicles with their offerings of heads taken in battle.Next, ikusagami are often found in the so-called books of military tactics including the Heiho Hijyutsu Ikkansho (Secret Art of Tactics) , thought to have been compiled in the Kamakura period. They are mainly mentioned in the context of invoking protection and success in battle, which is also commonly found in the treatise Shutsujin Shidai (Procedures for Going into Battle) . The term is also quoted in the Aro Monogatari (the Tale of the Crow and Heron) and not just in the books of military tactics; however, in these books descriptions of offering an enemy's head to ikusagami as seen in the war chronicles is rarely found ( although there are a few exceptions, which will be explained later) .In addition, the books of military tactics offer a vast range of gods both traditional and other than traditional to receive the prayers of warriors; Marishiten (a tutelary deity of samurais) and other various Shintoist and Buddhist deities can also be listed. In these books, an expression "ninety eight thousand ikusagami" often appears; despite this, the ikusagami of Japanese ancient times in rural areas such as Kashima, Katori or Suwa as found in the Songs to Make the Dust Dance hardly appear. The Edo period book Ikusagami: Questions and Answers written by Sadatake Ise refuted the concept of the "ninety eight thousand ikusagami" that appears in the world of the books on military tactics, and he also refuted the worship of Marishiten and other Shintoist and Buddhist deities as ikusagami. He went on to list Onamuchi no Mikoto, Takemikazuchi no Mikoto, and Futsunushi no Mikoto as Japanese ikusagami. His view is close to perceptions of the ikusagami in the rural Kashima or Katori mentioned in the Songs to Make the Dust Dance. Paradoxically what is revealed from Sadatake's description is that belief in the ikusagami of medieval warriors was not an orthodox belief in the gods of heaven and earth, which is traditionally found in Japan and actually connects the Songs to Make the Dust Dance with Sadatake Ise; medieval warriors actually incorporated various deities and beliefs including belief in a vigorous, powerful and sometimes impetuous deity. It is probable that esoteric Buddhism, ascetic practices in the mountains, and the Way of Yin and Yang resulted in a complicated syncretic fusion, and in response to the warriors' earnest demands for victory in battle, civilian religious figures created various kinds of magical belief.As described above, the ikusagami found in the war chronicles and those in the books of military tactics are different in nature; however, the phrase "a blood sacrifice to ninety eight thousand ikusagami" mentioned in the Tale of Soga, a book written entirely in kana syllabary, draws attention as a means to connect both concepts. Among the books on military tactics, Kinetsushu Volume 10 describes "how to make an offering of a head to a deity" in which a ritual offering a head to ikusagami is mentioned. Although these are just a few examples, they can be regarded as a successor of the ikusagami depicted in the war chronicles. The true state of such "blood sacrifice" is not exactly known, which leads to the need to examine the relation with China. In terms of words, a relation with an originally Chinese word 血祭 (kessai in Japanese pronunciation) needs to be considered; probably this word has a weak relation with the Japanese word 血祭り (chimatsuri, meaning blood sacrifice) , but with regard to the term 釁鼓 (kinko) found in the History of the Later Han, and meaning killing a person and smearing their blood on a hand drum, it is possible to think about the similarity to the Japanese 血祭り (blood sacrifice) .To answer the question whether the ikusagami to which a head is offered, as found in the war chronicles, is a term based on a sense of offering a sacrifice to a god, perhaps it is necessary to consider after careful examination of the expansion of such terms, classification of books of military tactics, and similar examples in the whole of East Asia.