typically short lived affairs, set up at a river bend or in a narrow canal that restricted the maneuverability of the boats. A wide variety of portable weapons were used in attacks, including recoilless rifles, B-40 rockets, .50 caliber machine guns and AK-47s, often fired from behind earthen bunkered positions. Engagements were brief and violent, with the ambushers often slipping away into the undergrowth when the boats located the source of attack and began to concentrate their return fire. When attacked the boats would accelerate out of the hot zone, turn and then return as a group, firing as many of their guns as they could bring to bear. They would power past the ambush point, turn and return to attack again until the ambushers were either killed or slipped away. Though most cruising and patrolling was done at 8 to 10 knots, the boats could reach a top speed of 32 knots. Thick brush and vegetation in the delta provided excellent cover for the escaping ambushers. Casualties taken among the river crews were high. Casualties suffered among the VC were difficult to assess, as they would take their dead and wounded away from a firefight. Discovering newly dug graveyards was one of the few ways to confirm VC losses. The first Swift Boat to be lost during the war was PCF-4, which was lost to a mine in 1966. Two boats, PCF-14 and PCF-76, were lost in rough seas at the mouth of the Cua Viet River near the DMZ, and a third, PCF-77, was lost in a rescue effort during a monsoon at the mouth of the Perfume River on the approach to Huế. All three of these boats were lost in 1966. PCF-41 was lost that same year in an ambush when it was hit by fire from a 57 mm recoilless rifle. Its controls destroyed and coxswain killed, it ran aground at speed. When the crew ran out of ammunition it had to be abandoned. It was recovered the next day but was too badly damaged to be repaired, so was salvaged instead. PCF-43 was lost to a rocket attack in 1969. Several other Swift Boats had been lost to river mines, but had been salvaged and either repaired or used for spare parts. Controversy over loss of PCF-19 On the night of 15/16 June 1968, U.S. marine aircraft spotters on the ground began reporting unidentified