Feb 5, 2018, 15:3302/05/18
I thought it was like the building/learning boosts. Any action started while the boost was active carried the boost until the action was complete. I have not tested this so I do not know for sure.I think they consider the march to the attack as a separate event from the actual attack, so if your boost expires during the attack march, you don't get them for the actual attack event.