During World War II, the depression's presence shaped the 1st and 2nd Battles of El Alamein. It was considered impassable by tanks and most other military vehicles because of features such as salt lakes, high cliffs and/or escarpments, and fech fech (very fine powdered sand). The cliffs in particular acted as an edge of the El Alamein battlefield, which meant the British position could not be outflanked. Both Axis and Allied forces built their defences in a line from the Mediterranean Sea to the Qattara Depression. These defences became known as the Devil's gardens and are for the most part still there, especially the extensive minefields. No large army units entered the Depression, although German Afrika Korps patrols and the British Long Range Desert Group did operate in the area, as these small units had considerable experience in desert travel.[12][13] The RAF's repair and salvage units (e.g. 58 RSU) used a route through the depression in order to salvage or recover aircraft that had put down in the Western desert away from the coastal plain. The RSUs included a 6-wheel drive truck, Coles crane, and large trailer, and were particularly active from mid-1941 when Air Vice-Marshal G.G. Dawson arrived in Egypt to address the lack of serviceable aircraft.[14]
The German officer stationed in the depression was cited by Gordon Welchman as helpful in the breaking of the Enigma machine code, due to his regular transmissions stating there was "nothing to report".[15]
