a. Have/has is necessary for present perfect (or any perfect tense). After wounded makes no sense. You could say "after he was wounded". The difference between these is that 'having been' (present perfect continuous) is used to talk about events that continue to happen up until the present while 'after he was wounded' (past simple) suggests that the action of being wounded occurred in the past and is completed. Look at the timeline on this page, and then look at the little graphs on present and past perfect as well. They might help you understand it better. http://www.englishpage.com/verbpage/presentperfectcontinuous.html It's a very subtle difference in the language, and most native speakers won't even be able to explain the difference between present perfect and past simple. b. Present perfect is used to talk about a completed action at an unspecified time in the past. Past perfect is used to talk about a completed action before something in the past. (He was sent to the hospital because he HAD been injured. First he was injured, then he was sent to the hospital) I could be wrong here, but I think the second part of the sentence you use as the example is written wrong. It does sound a bit clunky and after thinking about it a bit and checking the definition of past perfect I think the word 'had' is being used incorrectly here. The sentence probably should be "After having been wounded towards the end of the war, he WAS sent to the hospital". In this case you can picture the soldier being shot, being carted off the front lines by medics, and being put in a truck and transported to the hospital, still wounded. Hope that helps.