The US Navy was a refuge from the war
During the Vietnam War US navy enlistments went up due to many choosing to serve in the Navy to fulfill their service obligation and avoid the draft. The Navy was heavily involved in Vietnam, from launching air strikes from its carriers, bombarding the coasts from its gunships, and patrolling the rivers and coastal waters with what became known as its brown water Navy. From 1965 to 1970 the Navy almost completely stopped the traffic by water in weapons and other supplies meant to equip the North Vietnamese Army and the Viet Cong.
As American losses of aircraft increased in the 1960s the Navy brought the battleship New Jersey out of mothballs and by the fall of 1968 the ship was bombarding targets along the DMZ. The battleship targeted storage bunkers, troop concentrations, radar installations, and engaged with shore batteries. Throughout the fall of 1968 New Jersey responded to calls for artillery support. New Jersey was supplemented by the smaller guns of many destroyers and other ships operating along the coast, and provided support to Army troops and Marines as needed, replenishing in Singapore or Australia. In 1969 New Jersey was again designated to be inactivated, due to the cost of operations.
US Navy aircraft carriers launched bombing missions and provided fighter support throughout the Vietnam War. In the defense of Khe Sanh in 1968, Navy planes delivered about 50,000 tons of bombs on the positions of the troops besieging the US Marines there. The Navy attacks were supplemental to the bombing by the US Air Force, which included B-52s which flew in from bases in Guam and Okinawa. Navy ships stood by as both radar picket ships communicating enemy aircraft positions to pilots, and as safety guards to send helicopters to rescue downed pilots.
The United States Navy, supported by the United States Coast Guard and the South Vietnamese Navy imposed a blockade of South Vietnam from 1965 to 1970 known as Operation Market Time. Any vessel which approached within 12 miles of the South Vietnamese coast could be stopped and searched. If contraband was discovered the vessel was seized. The Navy extended this blockade and search authority to the rivers and streams of the country, and any vessel could be stopped at any time. The search authority extended to checking the identity papers of individuals on board a vessel, and the detaining of those deemed suspicious.
The effectiveness of the blockade was evident when between 1967 and 1969 no trawlers attempted to run through it, as they had in the earlier days of the war. In one such event in 1967, four trawlers attempted to slip through the blockade. Three were destroyed by Navy ships and the other turned back. The Navy’s interdiction forced the communists to use the much slower Ho Chi Minh trail for resupply. The US Navy had 2,556 service members killed during the war. Over 100,000 Navy personnel served in the Vietnam theatre of operations on ships and shore facilities built during the war.