Editing Qattara Depression (section)

==History==

=== Measurement ===
The elevation of the depression was first measured in 1917 by an officer of the British Army leading a light car patrol into the region. The officer took readings of the height of the terrain with an [[barometer|aneroid barometer]] on behalf of [[John Ball (geologist)|John Ball]], who later would also publish on the region. He discovered that the spring Ain EI Qattara lay about {{convert|60|m|ft}} below sea level. Because the barometer got lost and the readings were so unexpected, this find had to be verified. During 1924–25, Ball again organised a survey party, this time with the sole purpose to [[triangulate]] the elevation on a westerly line from [[Wadi El Natrun]]. The survey was led by G.F. Walpole who had already distinguished himself by triangulating the terrain across {{cvt|500|km}} from the [[Nile]] to [[Siwa Oasis|Siwa]] via [[Bahariya]]. He confirmed the earlier readings and proved the presence of a huge area below sea level, with places as deep as {{convert|133|m|abbr=on}} below sea level.<ref name="El Bassyony" />

Knowledge about the geology of the Qattara Depression was greatly extended by [[Ralph Alger Bagnold]], a British military commander and explorer, through numerous journeys in the 1920s and 1930s. Most notable was his 1927 journey during which he crossed the depression east to west and visited the oases of [[Qara Oasis|Qara]] and [[Siwa Oasis|Siwa]]. Many of these trips used motor vehicles ([[Ford Model-T]]s) which used special techniques for driving in desert conditions. These techniques were an important asset of the [[Long Range Desert Group]] which Bagnold founded in 1940.<ref name="Bagnold1">{{cite journal | url=https://www.jstor.org/stable/1784992 | jstor=1784992 | title=Journeys in the Libyan Desert, 1929 and 1930 | last1=Bagnold | first1=R. A. | journal=The Geographical Journal | year=1931 | volume=78 | issue=1 | pages=13–33 | doi=10.2307/1784992 | url-access=subscription }}</ref>

After the discovery of the depression, Ball published the triangulation findings about the region in October 1927 in ''[[The Geographical Journal]]''. He also gave the region its name "Qattara" after the spring Ain EI Qattara where the first readings were taken. The name literally means "dripping" in Arabic. Six years later in 1933, Ball was the first to publish a proposal for flooding the region to generate hydroelectric power in his article "The Qattara Depression of the Libyan Desert and the possibility of its utilisation for power-production".<ref name="El Bassyony" />

===World War II===
During [[World War II]], the depression's presence shaped the [[First Battle of El Alamein|First]] and [[Second Battle of El Alamein|Second Battles of El Alamein]]. It was considered impassable by [[tank]]s and most other [[military]] [[vehicle]]s because of features such as salt lakes, high cliffs and/or [[escarpment]]s, and [[fech fech]] (very fine powdered sand). The cliffs in particular acted as an edge of the El Alamein battlefield, which meant the Allied forces could not be [[flanking manoeuvre|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.

No large army units entered the Depression, although German [[Afrika Korps]] patrols and the British [[Long Range Desert Group]] did operate in the area, since these small units had considerable experience in desert travel.<ref name="Bagnold1" /><ref>Jorgensen, C. (2003). ''Rommel's panzers: Rommel and the Panzer forces of the Blitzkrieg, 1940–1942'' (pp. 78–79). St. Paul, MN: MBI.</ref> The RAF's repair and salvage units (e.g. 58 RSU) used a route through the depression to salvage or recover [[aircraft]] that had landed or crashed in the Western desert away from the coastal plain.

The RSUs included six-wheel-drive trucks, Coles cranes, and large trailers, and were particularly active from mid-1941 when [[Air Vice-Marshal]] G.G. Dawson arrived in Egypt to address the lack of serviceable aircraft.<ref>Richards, D., Saunders, H. (1975). ''Royal Air Force 1939-45'' Vol II (pp 160-167). Stationery Office Books</ref>

A German communications officer stationed in the depression was cited by [[Gordon Welchman]] as being unintentionally helpful in the breaking of the [[Enigma machine]] code, due to his regular transmissions stating there was "nothing to report".<ref>{{cite book|last=Lee|first=Lloyd|title=WWII: Crucible of the Contemporary World : Commentary and Readings|year=1991|publisher=M.E. Sharpe|pages=240|url=https://books.google.com/books?id=3l_vg1p5EHsC&q=qattara+depression&pg=PA240|isbn=9780873327312}}</ref>