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 Empire's forces could not be outflanked to the south. 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 they are for the most part still there, especially the extensive minefields.