the South Vietnamese had already built a strong defense on Southwest Cay, thus deterring any potential counter-attack. Later Southwest Cay would be the first major target for the VPN. Prelude North Vietnam On April 4, 1975, the High Command of the VPN and the Command of Military Region 5, under the command of General Chu Huy Mân, agreed on a plan to seize some Spratlys and other groups of islands. Under their secret plan, the VPN deployed the 126th Battalion, a naval special forces unit of about 170 personnel, to join the VC 471st Battalion of Military Zone 5. They were supported by three transport ships, the T673, T674 and T675 along with 60 experienced sailors and technicians from the 125th Naval Transport Brigade. The operation would commence at 12.00 am on April 9, 1975, to coincide with the PAVN ground attack on Xuân Lộc and to take advantage of low tide to land the special forces on the South Vietnamese-occupied sections of the Spratly Islands. To maintain the secrecy of their operation, the VPN kept their radio communications to a minimum in the days leading up to the attack. South Vietnam Unlike their North Vietnamese counterparts, South Vietnam possessed a large naval force with a strong fleet of ships. Hence the Republic of Vietnam Navy (RVN), commanded by Vice Admiral Chung Tấn Cang, were able to maintain a strong presence in the Spratly Islands, with only a handful of infantry units provided by the ARVN to protect the smaller islands surrounding the main Spratly Island. To defend the islands, ARVN forces were mainly equipped with small infantry weapons, as well as M-72 anti-tank weapons. Whenever necessary, the RVN could deploy the destroyer , the frigates , and , as well as the corvettes and to provide fire support. The RVN also relied on two transport ships, namely the and , to transport vital supplies and reinforcements to ARVN forces on the Spratly Islands. Battle Southwest Cay On April 9, 1975, three VPN transport ships, disguised as fishing trawlers, began moving towards Southwest Cay in the Spratly Islands with members of the 126th and 471st Battalions all on board. On the morning of April 11, 1975, helicopters from the United States Seventh Fleet began circling the VPN transport ships, but they were allowed to move on as the disguised North Vietnamese ‘fishing trawlers’ were mistakenly identified as ships from Hong