also: そなえたて
noun
disposition of troops; battle formation
Archaic military term referring to the arrangement or formation of troops before battle. Not used in modern Japanese outside historical contexts.
戦国時代の文献には、備立ての図がよく描かれている。
In documents from the Warring States period, diagrams of troop dispositions are often drawn.
この合戦では、巧妙な備立てが勝敗を分けた。
In this battle, the clever battle formation decided victory or defeat.
陣形 is the modern and general term for battle formation, while 備立て is an archaic term specifically for the disposition of troops.
Compound of 備え (sonae, 'preparation, military arrangement') and 立て (date, 'arrangement, formation'). The exact historical derivation is uncertain, but it is an archaic military term.