rear guard; reserve troops
Military term for troops positioned at the rear, either as a guard or as a reserve force. Used in historical or strategic contexts.
They strengthened the rear guard to prepare for the enemy's pursuit.
The reserve troops have not yet joined the battle.
後陣 is the rear guard that follows behind, the opposite of 先陣, the advance guard that goes first.
afterpains; involution
Compound of 後 (rear) and 陣 (camp, battle formation). The exact historical derivation is uncertain, but the word follows standard Sino-Japanese military terminology.