分析we take increased devotion to that cause for which they gave the last full measure of devotion.It is rather for us to be here dedicated to the great task remaining before us; that from these honored dead,we take increased devotion to that cause

分析we take increased devotion to that cause for which they gave the last full measure of devotion.It is rather for us to be here dedicated to the great task remaining before us; that from these honored dead,we take increased devotion to that cause
分析we take increased devotion to that cause for which they gave the last full measure of devotion.
It is rather for us to be here dedicated to the great task remaining before us; that from these honored dead,we take increased devotion to that cause for which they gave the last full measure of devotion.
后面这一部分怎么分析?for which怎么分析?

分析we take increased devotion to that cause for which they gave the last full measure of devotion.It is rather for us to be here dedicated to the great task remaining before us; that from these honored dead,we take increased devotion to that cause
for which 引导定语从句修饰cause,表目的.
这应该是一个纪念活动演说,因此做了一些加译,供参考：
我们今天来到这里,就是为了去全力完成摆在我们面前的光荣而又伟大的任务；为了这一目标,英勇的先烈们前赴后继,赴汤蹈火,流尽了最后一滴血,我们一定要秉承先烈遗志,更加努力,更加顽强,为实现这一远大目标,不畏艰险,勇往直前.