Inamuragasaki Reef Operation (Medieval Siege of Kamakura)
In medieval Japan, Yoshisada Nitta(warlord) besieged the capital Kamakura in order to overthrow the Kamakura government, and after about a week of siege, it fell.
What seems to have been the beginning of the capture is the current plan to cross the reef from Inamuragasaki.
In Kamakura, which is surrounded by mountains to the east and west, and the sea is approaching to the south, after capturing Mt. Ryozen at the western end, taking advantage of the opportunity that the cliffs of the mountain became shallow due to low tide, the army was forced to cross the reef. There is a powerful historical theory that he raided Kamakura from
In order to enable reef crossing operations that take advantage of low tides, it would be impossible to formulate operational plans without detailed intelligence on weather and topography.
It may be difficult even with satellite image analysis (imint) (of course, there were no reconnaissance satellites in the Middle Ages). Interception of communication information (signatures) (capture of letters, etc.) would have been impossible during the one-week siege.
After all, it is highly likely that the decisive intelligence came from local residents such as local fishermen, officers familiar with the area, and allied officers who knew how to use the topography (Humint).
In order to acquire the above intelligence, it is essential to win the hearts of the people, build trust with allies, and embed and acquire information sources to enemies and enemy territories.
I think it can be asserted that the strength of the Nitta army at that time was more than the superiority of numbers.
中世日本において鎌倉政府を打倒すべく新田義貞が首都鎌倉を包囲し、約1週間の包囲戦の後に陥落させた。
攻略の端緒となったと思われるのは、現在の稲村ヶ崎からの渡礁作戦。
東西北をを山に囲まれ、南に海が迫る鎌倉において、西方端の霊山山を攻略したうえでその山の崖下が干潮で浅瀬となった機に乗じて軍を渡礁させ、裏手から鎌倉を急襲したという有力な史説がある。
干潮に乗じた渡礁作戦を可能にするためには、気象と地形に関する詳細なインテリジェンスがなければ作戦計画の立案自体が不可能なはず。
衛星画像解析（イミント）によっても困難なのではないか（もちろん中世には偵察衛星など存在しない）。通信情報（シギント）傍受（書状の奪取など）は、僅か1週間の包囲戦では無理だったと思われる。
やはり、決め手となるインテリジェンスは、地元漁師等の現地住民や現地に詳しい将校、地勢を利用することに明るい味方将校からもたらされた可能性が高いのではないか（ヒューミント）。
上記のインテリジェンスを獲得するためには、民心収攬や味方との信頼関係構築、敵や敵地への情報源の埋め込みや獲得が欠かせない。
当時の新田軍の強さには数の優位以上の強さがあったことだけは断言できると思う。