Jill, adamste81's explanation is essentially correct. The sentence seems to be a proposal for the future. Here are some more details. division headquarters= the command center of a National Guard Division located in one of the 50 states of the USA civil support division= a specially trained Division of the National Guard (trained for emergency response) When a civil support division of the National Guard is deployed in a catastrophic emergency, they will have their own headquarters in the disaster zone, but the division headquarters in their home state will remain the higher headquarters. The more robust (stronger) division headquarters at home will support and if needed completely take over the civil support division headquarters. The strength of this command structure will allow the division to move quickly in and out of a disaster zone.

Having a division headquarters identified to be the higher headquarters of a specified civil support force during a catastrophic emergency would enable that force to deploy rapidly into a disaster zone during the initial phase of a crisis response. This will be supported by, and eventually subsumed by, the more robust division headquarters if the disaster so warranted. Which I have re-written the sentence the way it looks correct to me. This is actually two sentences, not one, and the last word “which” seems to be the beginning of another sentence. You will never find a sentence in English that ends in the word “which”. Hope this makes sense. As far as what it means it seems to be saying that during a catastrophe there would be a division of a civil support to be the first on the scene of a disaster. Their job would be to be the first ones on the scene, and then if the catastrophe so warranted (if it was bad enough) the other parts of the division would come and take over and regain control of the situation.