During the Second World War, the central Mediterranean island of Malta was famously besieged by the Italian navy and intensively bombed by Italian and later German air forces, from June 1940 until Allied victory in North Africa in May 1943 brought an end to the siege. It was then scheduled as a staging post to support the Allied invasion of Sicily from North Africa in July 1943 and of mainland Italy from Sicily in September. From 1941 until 1945, two Tunnelling Companies Royal Engineers, overlapping in succession, excavated underground facilities safe from aerial or naval bombardment. In 1943 and then 1944–1945, two Boring Sections Royal Engineers in succession drilled wells to enhance water supplies, initially for increased troop concentrations. Borehole site selection was guided in 1943 by the Director of the Geological Survey of Great Britain (Edward Battersby Bailey: 1881–1965) and by geologists Captain Frederick William Shotton (1906–1990) and Major Gordon Lyall Paver (1913–1988). In 1944, it was guided by geologist Captain Howard Digby Roberts (1913–1971), leading a detachment from 42nd Geological Section of the South African Engineer Corps that pioneered earth resistivity surveys on the island. Overall, these military studies generated a new but unpublished geological map of the island at 1:31,680-scale and refined knowledge of its geological structure: a much faulted but otherwise near-horizontal Oligo-Miocene sedimentary sequence. Further refinement was achieved as a consequence of the 1944–1945 drilling programme, led principally by geologist Captain Thomas Owen Morris (1904–1989) of the Royal Engineers. By 1945, this had helped to develop an improved water supply system for the island, and plans to develop groundwater abstracted from a perched upper aquifer (in the Upper Coralline Limestone and underlying Greensand formations, above a ‘Blue Clay’) as well as from the main lower aquifer, near sea level (in the Globigerina Limestone and/or underlying Lower Coralline Limestone formations).