[1] French plans for defence of Tunisia assumed that Italy would launch an overwhelming assault that France could not easily oppose.

Italy was expected to launch attacks on Egypt and Tunisia as soon as war was declared, with the Italian Navy securing supply and blocking any substantial Anglo-French relief.

The primary feature in the south is the Matmata Hills, a range running north-south roughly parallel to the Mediterranean coast.

The plain consists of gravels and sands, with salt flats between the sandy areas, which turn into bogs after light rain becoming impassable to wheeled vehicles.

Inland, the sources of the wadis are steep and rocky, widening near the coast, the beds having streams or muddy bottoms, with firmer areas traversable by vehicles.

[5] In January 1934 planning began on the new fortifications; Infantry officers selected the sites for strongpoints to dominate the ground in front with overlapping fields of fire.

[6][b] The casemates designed for the line had much less concrete than comparable examples in France and had no fossé (gap) rather a stable door, in case the lower part was blocked by débris.

General Georges Catroux and Colonel Gautsch surveyed the area and in their assessment predicted that three divisions could advance from the Libyan border to Ksar (fortified village) el Hallouf and Bir (well) Soltane in six days and then advance into the gaps either side of Djebel Melab and those between Djebel Tebaga and the Matmata Hills.

Some of the flanking casemates for machine-guns covering the gaps were connected by galleries; strongpoints on the plain and in hills had anti-tank positions.

[6] In the Matmata hills, Ksar el Hallouf covered an anti-tank ditch which continued the position beyond the main line which ended on the foothills.

An infantry position was dug into the Matmata hills at Ksar-el-Hallouf and in the Dahar beyond, a strongpoint at Bir Soltane had two 75 mm turrets, removed from Char 2C tanks built in 1918.

At Ben Gardane an advanced position was built consisting of a square redoubt inside an anti-tank ditch with casemates on the flanks and concrete infantry shelters.

Axis engineers built an outpost zone from Wadi Zeuss 3.5 mi (5.6 km) back to the Mareth Line.

South of "La Spezia", near Beni Kreddache covering the Hallouf Pass the line was held by the 164th Light Afrika Division.

This success, combined with another frontal assault on the Mareth Line, made the position untenable; the Italian 1st Army escaped encirclement when the 1st Armoured Division was held up at El Hamma and the Axis forces retreated to Wadi Akarit, 37 mi (60 km) to the north.