Bukhaari:V4B52N256 "The Prophet passed by and was asked whether it was permissible to attack infidels at night with the probability of exposing their women and children to danger. The Prophet replied, ‘Their women and children are from them.'"
Having been quoted the above hadith, "Kevin" asked me to check the authenticity and then find out what Muslim scholars had to say about it. He then suggested that possibly the women and children might have been enlisted to fight and were therefore legitimate targets. This was my reply:
So the evidence from this apparently utterly reliable hadith (I'm going on what Muslims have to say about the hadith here) is that Mohammad did not always spare innocents in warfare.