[1] Operation Castor recaptured and then established a fortified airfield in Điện Biên Phu, in the north-west corner of Vietnam.

This is the home of various ethnic mountain people, called Montagnards – primarily Hmong, Tho, Muong, T'ai, Nung, Yao - not related to the majority Kinh Vietnamese.

These T'ai related forces supported the French in guerrilla operation against the Viet Minh bases in the upper Tonkin.

Some of the more successful commando raids in 1953, such as the attack on the twin towns of Coc-Leu and Lai Cai in October made it necessary for the Viet Minh to ask for Chinese troops to cross into Tonkin to help defeat the "rebels", which they in fact did on more than one occasion.

[3] Operations Castor and Pollux were meant to re-assert French control of Dien Bien Phu after it had been overrun by the Viet Minh in the Black River Offensive of 1952.

40 (issued on January 10, 1953) stated: "The reoccupation of Dien Bien Phu must constitute in the forthcoming period the first step for regaining control of the T'ai country and for the elimination of the Viet Minh from the area west of the Black River.

After the French chose the Dien Bien Phu plateau for the ultimate confrontation with the Viet Minh (and took the area back on November 20–22 in 1953 in Operation Castor), they decided to withdraw from the less defended Lai Châu area and to repatriate the inhabitants from there to Dien Bien Phu.

As a token of respect for their long-time ally Đèo Văn Long, the French sent General Cogny personally to summon Đèo Văn Long and the white Tai people to abandon their traditional home and move (to where the battle was to be ultimately fought).

[6] On December 11, the forces entrenched in Dien Bien Phu then made a major effort to reach and aid the guerrillas moving from Lai Châu.

[7] After this failure, the same 2nd Airborne Battle Group sent a sortie south to link up with a combined French /Laotian force near Sop Nao.

But now the French command there saw the exact opposite – the difficulty in using troops at the base to disrupt Viet Minh activities in this area.

They helped build and support the unprecedented artillery pounding and the encircling and undermining of the French outpost in what was ultimately the decisive battle the First Indochina War.