of the proposed line, Tataouine being the place where the routes to Mareth passed through the bottleneck between the Matmata Mountains and the sea. The line was divided into eastern and western sectors with a main line of resistance and a reserve line about back. A (SD) was to be built on the rocky Dahar Plateau, which later became part of an SD across the Matmata Hills to Kebili on the edge of the Chott el Djerid. The chott and Chott El Fedjaj drained across Tunisia into Wadi Akarit, across Tunisia but Wadi Akarit was only sketchily fortified, the French concentrating on the Mareth Line south, to cover Gabes. The gap between the Mareth Line and the Great Eastern Sand Sea, a potential route by which an invader could outflank the Mareth line, was not given consideration until 1938. 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. Mareth Line The Mareth Line consisted of casemates surrounded by barbed wire and built for all-round defence in the main and reserve lines, the obstacles being doubled on the fronts and sides. The strongpoints in the main line included flanking machine-gun casemates and anti-tank gun positions; in the reserve line artillery emplacements provided covering fire in the gaps between the strongpoints in the main line. 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. An anti-tank obstacle of vertical rails was built along the front of the line and the sides of Wadi Zigzaou were steepened. Eight artillery casemates, forty infantry casemates or blockhouses and fifteen command posts were built. The eastern sector had twelve strongpoints in the main line and eleven in the reserve line. The western sector had eleven strongpoints in the main line and seven in the reserve line. 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