Drang Valley, depleted, the division leapfrogged west, clearing Route 9, until at 0:800 hours 8 April, the 2nd Battalion, 7th Cavalry, linked-up with Marines at the combat base, ending the 77-day siege. On 19 April 1968, as the 2nd Brigade continued pushing west to the Laotian border, the 1st and 3rd Brigades (about 11,000 men and 300 helicopters) swung southwest and air assaulted A Shau Valley, commencing Operation Delaware. The PAVN was a well-trained, equipped, and led force. They turned A Shau into a formidable sanctuary —complete with PT76 tanks; powerful crew-served 37mm antiaircraft cannons, some radar controlled; twin-barreled 23mm cannons; and scores of 12.7mm heavy machine guns. A long-range penetration operation was launched by members of the Division's long-range reconnaissance patrol (LRP) against the PAVN when they seized "Signal Hill"—the name attributed to the peak of Dong Re Lao Mountain, a densely forested mountain midway in the valley—so the 1st and 3rd Brigades, slugging it out hidden deep behind the mountains, could communicate with Camp Evans near the coast or with approaching aircraft. Despite hundreds of B-52 and jet air strikes, the PAVN forces shot down a C-130, a CH-54, two Chinooks, and nearly two dozen UH-1 Hueys. Many more were lost in accidents or damaged by ground fire. The division also suffered more than 100 dead and 530 wounded in the operation. Bad weather aggravated the loss by causing delays in troop movements, allowing a substantial number of PAVN to escape to safety in Laos. Still, the PAVN lost more than 800 dead, a tank, 70 trucks, two bulldozers, 30 flamethrowers, thousands of rifles and machine guns, and dozens of antiaircraft cannons. They also lost tons of ammunition, explosives, medical supplies and foodstuffs. In mid-May 1968 Operation Delaware ended, however, the division continued tactical operations in I Corps as well as local pacification and "medcap" (medical outreach programs to local Vietnamese). In the autumn of 1968, the division relocated south to Phước Vĩnh Base Camp northeast of Saigon. In May 1970, the division participated in the Cambodian Incursion, withdrawing from Cambodia on 29 June. Thereafter, the division took a defensive posture while US troops withdrawals continued from Vietnam. On 29 April 1971 the bulk of the division was withdrawn to Fort Hood, Texas, but its 3rd Brigade remained as one of the final two major US ground combat units in Vietnam, departing 29 June 1972. However, its 1st