Rereading the VIetnam War I was struck by why there was no attempt at all to invade the North. IMO it seemed the US Army was just bidding it's time fighting a protracted insurgency hoping to bleed the Viet Cong white through attrition warfare. With over 600,000 troops by 1967, they certainly had the manpower so how would a concerted campaign to take Hanoi affected the outlook of the war?