The WWII flame barrage

By Rob Morgan

Lord St. Vincent said of Bonaparte’s rag-tag and bobtail, ‘I do not say they cannot come, I only say they cannot come by sea.’ Now this is another of those intriguing weapons devised to prevent, in this case, a German invasion. The May 2017 issue The Mariner’s Mirror (Vol. 103:2) contains a short description by R.G. Hart (pp.217-219) of the 50 miles or more of ‘flame barrage’ intended to be installed along the south coast of England to oppose Operation Sea Lion early on in the war. In fact, the actual length of flame barrage defences turned out to be only 10 miles or so at some key invasion threatened points, but Hart provides a decent, readable account of the research and development of this amazing weapon.

The oil fuel was supplied by two large bowsers — tankers on land — through underwater pipes. A range of fuels were used, petrol, diesel and heavy viscous oil, and it seems from detailed test results that a ‘…boat stopping … continuous bank of flame and smoke fully thirty yards in width’ could be controlled and adjusted for 30 minutes, consuming only four tons of fuel! A good, useful wargame point that, of course! The weapon was ignited incidentally by Admiralty pattern flare canisters, remotely operated on the sea-bed.

The results varied according to wind and weather, but a fair assumption given the quality of attack craft available in the first two or three years of war would be that any invasion would have to be attempted in decent weather. Part of the flame installation, almost all of which was underwater scaffolding, suffered damage in late 1940 during a storm (shades of Mulberry Harbour) and though the usual reason for no invasion taking place (the Royal Navy, of course, ably assisted by the RAF) prevailed, a bizarre cohort of legends grew up around the Flame Barrage. The writer also provides four titles which deal with this device, and there seemed to be potential for a larger weapon system.

A second ‘what if’ for wargamers in the East, deals with the capture of Singapore in 1942. Yamashita, commanding the Imperial XXVth Army, bombed and shelled the huge oil storage tanks on the island because the Germans had told him that the British could create a burning sea, and he feared the loss of his attack force in light boats crossing the Straits!

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