时间:on the day of his departure, 出发的那天 目的地: to a destination overseas , 国外的某个目的地 定语从句,where he would fight in the war, 参加战斗的地方 主句,he received her reply, 他受到了她的回信
One the day 是状语of his departure是定语 修饰the day,to a destination overseas是定语 修饰 departurewhere he would fight in the war是定语 修饰a destination ,he是主语 received是谓语 her reply是宾语.