"我们现在开始突围,坚决完成任务"

We begin to sally out now, and we are resolute to finish the mission.
注：
sally
/ ˈsælɪ; ˋsælɪ/ n
(a) sudden attack, esp by troops surrounded by the enemy 出击; （尤指）突围: make a successful sally 进行突围成功.
sally out/forth (fml 文) (a) emerge suddenly, usu from a place where one is surrounded, to attack an enemy 出击; 突围: sally out against the besiegers 向包围的敌人出击. (b) (joc 谑) set out somewhere or to do sth 出发; 着手做某事: Party workers sallied forth in a drive to find new members. 党的工作人员发起了纳新运动.

Let's start breaking the siege now. We must accomplish the mission no matter what.

Now we start to sally,determined to complete our task.