Only the passage of Trung Ha remained open and the group had to use it very quickly under the pressure of an adversary whose first armored vehicles came into contact with our rear guards from 10:30 a.m. on March 10. Despite the Japanese attacks, almost all the personnel succeeded in crossing the river, the last elements under enemy fire, but the loaded trucks and the guns, which could not use the bins, were set on fire or rendered unusable.
The Potez from the Tong airfield, which were supposed to fly away at daybreak, fell into the hands of the Japanese who had infiltrated the airfield during the night. They will not use these old devices which we will nevertheless miss sorely:our means of liaison and observation are indeed reduced to the 3 or 4 devices absent from Tong on the night of March 9 to 10.
On March 11 the group finds itself near Thu Cuc (see map), practically without supplies from any practically Forced to live in the country, General Alessandri, to reduce his manpower which could not survive in these sparsely inhabited regions and without great resources, decides to separate from the Indochinese who will be demobilized during the day. To also facilitate supplies, what remains of the group (about 1,500 men including 800 legionnaires) is divided into two sub-groups - Colonel François and Commander Prugnat. The first will move between the Black River and the Song Ma towards the Meos Pass. Prugnat (2/5e R.E.I. - 3/4e R.A.C. - D.M.C. - airmen) will join Phong Tho via Nghia Lo, Thu Le and Than Uyen, between the Black River and the Red River, in order to ensure a flank-guard to the François column and, possibly, a connection with our elements of the Claire River, east of the Red River.
On March 12, two “Liberators” parachuted in weapons and ammunition. Others are requested and hoped for. Reinforcements are expected until March 24, when General Alessandri meets in Dien Bien Phu Commander Baume, sent by Calcutta. There will be no reinforcements, "the Allies having not made known their intentions as to the transport, in the Far East, of our C.L.I.". Under these conditions, the fight in retreat can only continue with the meager reinforcement of the troops of the 4th military territory (T.M.) of Lieutenant-Colonel Fourmachat and the battalion of Commander Euzières (5th T.M.).
On each major cut, at each pass, our troops are fighting to "stay as long as possible in Indochinese territory" in accordance with orders.
Moc Chau falls on March 19, Son La on the 25th, Dien Bien Phu on April 4, Muong Khoua on the 12th, Boun Tai on the 22nd (see map). Since April 6, what remains of the Prugnat column, since the 2/5e R.E.I. was taken from him to reinforce the defense of Son La, passed into China by Ban Cuong after having stopped the Japanese at Pou Kan Sap and evacuated this position on order.
The Fourmachat 1 sub-group About 500 men, including 300 Europeans, evacuated Lai Chau on April 2 and retreated via Po Bai, Muong Tong, Muong Nhie. This subgroup will go to China at Pa Chan on April 29th. General Sabattier, new delegate general of the G.P.R.F., joined Xu Tung the day before. General Alessandri, after a final request for reinforcements in Calcutta on April 3, decided to leave Indochinese territory on May 5.
With insufficient rations - often only rice -, a heterogeneous and partly outdated armament, little ammunition, uniforms in rags, without shoes, the French forces faced, for two months, Japanese columns with a modern weaponry. While fighting, these troops marched for hundreds of kilometers through difficult bushland, in a region of rugged terrain, often on barely marked tracks.
The aid provided by the 14th U.S.A.F., without having been what it could have been, nevertheless relieved our troops by several interventions against the Japanese columns and two or three parachute drops.
Under the orders of Colonel Seguin, the task of the Claire River group was to protect the left flank of the Alessandri group, near Tuyen Quang. The group also has a guerrilla mission east and north of the Red River. The G.R.C. has 3 battalions (2 and 4/9th R.I.C. - 3/10th R.M.I.C.), 3 batteries of 75 (4th R.A.C.), Cao Bang mobile detachment (3rd T.M.) and a number of mounted guard platoons Indochinese.