not move east until about 16:00 hrs. Just before dawn on September 17, two companies of the 5th Marines, supported by artillery and M26 tanks, defeated a counterattack by a column of six T-34 tanks and two hundred infantry, inflicting heavy casualties. Air attack on USS Rochester and HMS Jamaica Just before daylight at 05:50 on 17 September, two Soviet-made North Korean aircraft—probably Yakovlev Yak-9s—were seen overhead from Jamaica, and while trying to identify them any doubts about their allegiance and intentions were resolved by the explosion of a bomb close to the port side of Rochester. Four bombs were dropped, one hitting and denting Rochester's crane but not exploding. There were no American casualties. As the aircraft turned away Jamaica opened fire with her port 4-inch battery on the leading aircraft. The second aircraft then turned to port to strafe Jamaica, scoring several hits: one armor-piercing round entering Y turret through the armor at the back of the gun house and wounding a man in the leg; one chipping the side armor of the ship; one exploding round burst on the plate surrounding the loaders of a quadruple pom-pom, wounding three men (one of whom died later of his wounds after being transferred to the hospital ship ); and one on the foremast at the level of the gun direction platform, scattering small splinters. Every close range weapon available opened fire on this aircraft, which disintegrated as it went over the ship, crashing close to the starboard side of Jamaica. Breakthrough Kimpo Airfield The 2nd Battalion, 5th Marines flared off to the left (north) on September 17 to secure Kimpo airfield, west of Seoul. Kimpo airfield was the largest and most important in Korea. On September 17, General MacArthur was extremely urgent in his request for the early capture of Kimpo airfield. Once it was secured, the Fifth Air Force and USMC aviation units could bring fighters and bombers over from Japan to operate more easily against North Korea. The attack on Kimpo airfield was carried out by 2nd Battalion 5th Marines. The night of September 17–18 at Kimpo, the KPA unsuccessfully attempted to recapture Kimpo with those forces that had not already fled across the Han River, under the command of Brigadier General Wan Yong (the commander of the North Korean Air Force). The counterattacks were repelled by entrenched Marine Corps infantry, armor and artillery. By morning the