Bryn provided evidence from 1918.
Military tanks were a major invention of the First World War: developed during 1915 and first put into commission in 1916, they immediately captured the interest of the public, and tank entered into numerous compounds and phrases. However, we have not found any WWI-era evidence of the verb tank in a military sense (e.g. ‘to attack with a tank’ or ‘to travel by means of a tank or tanks’). The first quotations we have at present are from the 1930s (the first a figurative use):
Hymie scrams right out of town with him and they start to tank the country, flinging out the old challenge to any father of fourteen at catch weights.
1930 Amer. Mercury Dec., p. 417/2
There was an old Hoover Who lived in a shoe. He had so many vet’rans, He didn’t know what to do. So he gassed them and tanked them, And burnt up their beds.
1932 B. E. F. News 17 Sept., p. 5/1
The city crowds cheered, the armies went tanking forward.
1939 H. G. Wells Holy Terror iii. ii. p. 271
Although there is plenty of earlier evidence for the verb tank relating to the noun meaning ‘large receptacle’, we find it surprising that there are no earlier uses of the verb relating to the military vehicle. Is there evidence we haven’t found yet?
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To commemorate the centenary of the start of the First World War (1914–18), the OED is revising a set of vocabulary related to or coined during the war. Part of the revision process involves searching for earlier or additional evidence, and for this we need your help. Our first quotations are often from newspapers and magazines, and we know that there may well be earlier evidence in less-easily-accessible sources such as letters, diaries, and government records, many of which are now being made available in digital form for the first time.
Posted by OED_Editor on 30 January 2014 10.34