During the Battle of France, Kerfent was attacked by German forces, who captured the position from the rear after a short assault with artillery support.

The blocks are linked by deep underground galleries, which also provide space for barracks, utilities and ammunition storage.

[4] The 1940 manning of the ouvrage under the command of Captain Broché comprised 161 men and 2 officers of the 156th Fortress Infantry Regiment.

[10] The Casernement de Zimming provided peacetime above-ground barracks and support services to Kerfent and other positions in the area.

The following day the Wehrmacht attacked Kerfent with 88mm high velocity gunfire from a battery positioned atop Bambesch.

[12][13] Kerfent did not see significant action during the Lorraine Campaign of 1944, but the observation block's cloche was used for weapons tests by the Americans.

[14] After the war, Kerfent's combat blocks were mostly left in their damaged state,[15] but the underground facilities were cleaned and maintained.