'Jantzen' was an Allied one of several exercises undertaken in the UK to develop and practise the administrative and logistical support for the planned amphibious assault on North-West Europe which would mature as 'Overlord' (April/July 1943).
The object of this exercise was the rehearsal of the maintenance of a corps and supporting troops through the beaches for 14 days. The exercise was planned by the headquarters of Lieutenant General F. E. Morgan’s I Corps and Major General J. O. Carpenter’s (from 17 May Major General C. B. Wainwright’s) 61st Division on the basis of a two-brigade assault. On 22 July the I Corps carried out the administrative landings, under the direction of the headquarters of the Western Command, on beaches near Tenby in South Wales. Only administrative troops took part, but some 16,000 tons of stores were landed during the exercise.