 A short time later, their transmissions went dead and they were never heard from again.On 10 February two forward observers from the Marines' 1st Field Artillery Group were flown into Tây Lộc to help coordinate artillery and naval gunfire to support the fighting within the Citadel, however Trưởng instructed them that the Imperial Palace was not to be fired on.On 11 February the Vietnamese Marines Task Force A comprising the 1st and 5th Battalions, began to be lifted by helicopter into Mang Ca to replace the Airborne, however due to poor weather this deployment would not be completed until 13 February.