Final Answer:
The first post fell to the Vietminh within eight hours, thus the correct otpion is c.
Explanation:
The Battle of Dien Bien Phu was fought between French forces and the Vietminh, a communist-nationalist Vietnamese force, from March 13th until May 7th 1954. The French forces were defeated and the post fell within eight hours. This was an important battle in the First Indochina War, which lasted from 1946 until 1954.
The battle began when the Vietminh, led by General Vo Nguyen Giap, began a siege on the French base at Dien Bien Phu. The French had set up the base in order to establish a blocking position, to prevent the Vietminh from advancing further into Laos. The French forces, which were comprised of both French and Vietnamese soldiers, were outnumbered and outgunned by the Vietminh forces.
The Vietminh forces employed a strategy of artillery bombardment and infantry attacks to slowly wear down the French forces. The bombardment was effective and within two days, the first post had fallen to the Vietminh. However, the Vietminh could not completely overrun the base until May 7th, when the French commander, General Christian de Castries, surrendered the remaining French forces.
In conclusion, the first post fell to the Vietminh within eight hours of the siege beginning. This was a crucial victory for the Vietminh and allowed them to continue their march towards Laos, eventually resulting in the end of the First Indochina War.