Late March By late March, the FANK maintained a defensive perimeter some from central Phnom Penh. In the northwest, the 7th Division was in an increasingly difficult position; its front had been cut in several places, particularly in the region of Toul Leap which had changed hands several times. The 3rd Division, located on
Route 4 in the vicinity of Bek Chan (), some west of Pochentong, was cut off from its own command post at
Kompong Speu. In the south, the 1st Division handled the defense, along with the 15th Brigade of Brigadier General
Lon Non; it was the calmest part of the front at that time. In the region of
Takhmau,
Route 1 and the
Bassac River, the 1st Division was subject to continued Khmer Rouge pressure. East of the capital were the Parachute Brigade and the troops of the Phnom Penh Military Region. The MNK naval base on the
Chrouy Changvar peninsula () and the
Khmer Air Force (KAF) base at Pochentong were defended by their own forces. That afternoon Takhmau, the capital of the
Kandal Province and south of Phnom Penh, fell to the Khmer Rouge. The loss of this key point in the FANK defense perimeter had a demoralizing effect. Several counterattacks were initiated but to no avail. Soon a fierce battle was in progress in the southern suburbs. The U.S. aerial resupply into Pochentong was completely halted. The 15th began with the Khmer Rouge pressing in from north and west. Pochentong and the dike running east–west to the north of Phnom Penh, both of which formed the last ring of defense around the capital, were overrun by Khmer Rouge assaults. The intervention of the Parachute Brigade, brought back from the east of the Mekong, had no effect on the situation to the west of the capital. The brigade tried to move west, but was only able to get down Route 4.
17 April , Phnom Penh, 17 April 1975 At 02:00 on 17 April the Cabinet agreed that, as its peace offer had not been accepted, it would move the Cabinet, the Supreme Committee and even members of the Assembly from Phnom Penh to the north to the capital of
Oddar Meanchey Province on the Thai border in order to continue resistance from there. The only way to leave the capital was by helicopter. At 04:00 the members of the Government met in the garden in front of the Wat Botum Vaddey () for evacuation, but the helicopters did not show up. Admiral Vong Sarendy had returned to the naval base which was under attack by the Khmer Rouge. He called Sak later advising that the base was surrounded and about to be overrun. As Khmer Rouge forces entered the command post Sarendy committed suicide. By 08:00 the rest of the Cabinet, the deputies and the senators left the session, leaving Long Boret and Sak. General Thach Reng arrived to plead with them to leave with him, as he still had his men of the
Special Forces and seven
UH-1 helicopters at his disposal at the
Olympic Stadium. At approximately 08:30 Sak and his family boarded a helicopter and were flown out, as was KAF commander Ea Chhong. Meanwhile, Long Boret boarded another helicopter which failed to take off. Four helicopters flew to
Kampong Thom to refuel, arriving at 09:30. Establishing radio contact with Phnom Penh, Sak learned that the Khmer Rouge had penetrated into the General Staff Headquarters. General Mey Sichan addressed the nation and the troops in Sak's name asking them to hoist the white flag as a sign of peace. Sak's helicopter arrived at Oddar Meanchey at 13:30, as the collapse of the Republic was imminent. Any chance of reestablishing the Government evaporated and the assembled officers decided to seek exile in Thailand. Another column entered the city from the west over the Stoeng Mean Chey bridge along Monireth Boulevard. As the Khmer Rouge entered the capital in the north, a small group of soldiers and armed students, styled as the
MONATIO ("National Movement") and led by Hem Keth Dara, began driving around the city welcoming the arrival of the Khmer Rouge. MONATIO was apparently a creation of Lon Nol, in an attempt to ingratiate himself and share power with the Khmer Rouge. Initially tolerated by the Khmer Rouge, MONATIO members were later rounded up and executed.
Koy Thuon, a Khmer Rouge deputy front commander, organized the "Committee for Wiping Out Enemies" at the Hotel Monorom (). Its first action was to order the immediate execution of Lon Non and other leading government figures. Captured FANK officers were taken to the Hotel Monoram to write their biographies and then to the Olympic Stadium, where they were executed. ==Aftermath==