yes civil war. no colchester. Or at least not according to the inhabitants of gloucester. They say it was during the siege of gloucester, when the king's forces built a bridge (humpty dumpty) to cross the river and breach the wall. It was prefabricated, and fell into the water on being wheeled there. Has to be said that the provenance for this story is not good, so it may be that the colchester gun has it, but the gloucester one was the subject of at least one play (Revels and Devils...frequently a school production).