two sousand years ago ,a rich and powerful country ,cut down its trees to build warships ,(with)

two sousand years ago ,a rich and powerful country ,cut down its trees to build warships ,(with)wich to gain it self empire.为什么用的是with 呢。真的不理解。

先行词是warship 战舰战船
后面定语从句的意思是：以此（该国家）获得自己的领土。（有省略主语和谓语了it is） it is to gain it self empire with the warships
表示方式状语，如果没有with，warship在从句中无法用作正常的成分啊

你好！ 二sousand年前，一个富强的国家，砍伐树木建造军舰， 打字不易，采纳哦！