Citadel is GDW's simulation of the siege and capture of Dien Bien Phu. The following rules variants show what might have resulted had the French taken options that were historically ignored.

1. When firing at French artillery, all hits must be confirmed in the same manner that hits are confirmed on French Tanks.

This rule reflects the fact that the United States had offered the French in Indochina the types of body armor that had been used in Korea. The major problem for the French artillery crews at Dien Bien Phu was that the guns could not be effectively dug in, due to the need to have a 360 degree field of fire. Hence the crews of the 4th Colonial Artillery took very heavy losses. While it is true that the 105mm guns were vulnerable as well as the crews, it was easier to drop the gun parts than to replace the crews. Had the French used the body armor, they would have reduced casualties in the artillery crews, making it harder for the Viet Minh to knock out the French artillery.

2. The number of 105mm howitzer guns available to the French at the start of the game should be doubled.

This reflects the fact that the garrison was offered more artillery before the siege started, but felt that it was not necessary. Do not increase the number of units of 105mm guns, just the number of weapons in each unit.

3. Remove one or both of the parachute battalions in Dien Bien Phu at the start of the game. For each battalion removed, substitute two regular infantry battalions. One of the 4 may be Foreign Legion, two battalions may be colonial infantry (starting at 3-4, and changing to a 2-3 when flipped), and one battalion may be Algerian Rifles, similar to the 517. Once exchanged, the parachute battalions may not be returned.

This suggestion reflects the fact that the parachute battalions could have been withdrawn, and other leg infantry sent to take their place. While this rule seems to favor the French, in the long run it is not so. The additional troops allow Anne Marie to be held and for the garrison to reinforce some strong points, but the loss of the paratroopers will hurt the French player's chance of launching counter-attacks.

4. For each French battalion in the game, allow the French player two 75mm recoilless rifles. For the French player only, general supply is needed to fire them.

This suggestion reflects the fact that like most Western armies of this time, the basic battalion AT weapon was the recoilless rifle. The French had them, but did not carry them in the field due to a lack of targets, except on special operations. Had the French realized the other applications of these weapons, they might have been used at Dien Bien Phu. Remember that the recoilless rifle is a direct fire weapon.