Sentence:  By early summer , he wrote from Laramie that he was suffering from the wound inflicted in the <WSD>ambush</WSD> and was in a bad way financially , so Pels sent him a draft for $ 100 , warning that it was still not wise for him to return . 
Meaning of the word marked with <WSD> tags:  the act of concealing yourself and lying in wait to attack by surprise