Fort Driant was made from steel reinforced concrete; it was also surrounded by a deep dry moat and barbed wire.

The fort could also rain flanking fire that produced heavy casualties amongst the men of General Walton Walker's XX Corps.

[1] When the U.S. Third Army arrived at Metz, they were quickly drawn into a stalemate with the German defenders for weeks over control of the city and its perimeter.

On September 27, the failure of a regimental effort by 90th Infantry Division against Fort Jeanne d'Arc indicated to Third Army the inherent strength of the various fortified positions blocking entry into Metz.

B Company, 11th Infantry Regiment managed to breach the wire in the southwestern corner of the complex, owing to the attached tanks leading the assault.

E Company, under heavy fire and with its bulldozer-equipped tanks non-functioning, failed to breach the perimeter and dug in outside the wire for four days, losing 35 out of its 140 personnel.

[9] The commander of B Company, a Captain Anderson, discovered after repeatedly throwing grenades into a bunker that its occupants had withdrawn to the main fort through an underground tunnel.

Growing desperate to keep the attack's momentum, a self-propelled gun was brought to the front and fired at the barracks from a mere 30 yards (27 m) away, to no avail.

Kicking off the shafts' covers, he began shoving bangalore torpedoes into them, forcing its occupants to flee via underground tunnel to barracks 4.

However, one of the self-propelled guns managed to blast in the door to barracks 4 at close range, allowing the four surviving members of the platoon to enter and begin clearing the bunker.

In the daytime, German artillery fire from all surrounding areas focused on defending the fort and it became impossible to sustain the attackers who were already narrowly hanging on to the positions they had seized.

During the night time, the artillery barrages ceased and German troops emerged from the maze of concrete tunnels and viciously counterattacked the Americans' toehold on the fort, and completely isolating the attackers from any support.

[13] The task force commander received a set of detailed plans of the fort, and decided the attack should consist of a subterranean assault on a tunnel that connected the barracks held by US troops to the main barracks by way of the artillery batteries, with an attack on the surface to prevent the defenders from focusing their efforts on preventing the underground assault.

After the engineers successfully blew a hole in it, it was discovered that the door was backed by more than 20 feet (6.1 m) of scrap metal, concrete, and wrecked equipment, which had been stacked to the ceiling.

Due to the constant sound of digging on the German side of the tunnel, the Americans feared they would be counter-charged, and placed a 60-pound beehive charge against the door.

Before more explosives could be brought in, the Germans opened fire along the tunnel, forcing the Americans to build a sandbag parapet with a machinegun mounted on it.

Warnock suggested surrounding the fort and attacking it via tunnels, but Gay declined as the XX Corps lacked the manpower to do so.

The men of the 5th Infantry Division were thought to be becoming battle fatigued, and other line connecting operations were taking place around Metz with much greater success.

[17] Irwin was blamed by some for the failure at Fort Driant, for "moving too slow" and "removing the drive" of the battalion early during the initial attacks in September.

Patton's comment referenced the 5th Infantry Division being saturated with new troops, as it had suffered heavy casualties at Dornot in September, with some battalions almost entirely destroyed.