The unusually fluid battle conditions on the vast expanse of desert in the Second Libyan Campaign, when there was no defined line between the opposing forces and supply lines were upset, created for the field medical units peculiar circumstances which were not repeated in later campaigns. All the field medical units, with the exception of B Company 4 Field Ambulance which formed the ADS for 4 Infantry Brigade, were at one time or another in the hands of the enemy. Most of the men of 4 Field Ambulance, and B Company 5 Field Ambulance, some of A Company 6 Field Ambulance, some of 4 Field Hygiene Section, and the Mobile Surgical Unit (less drivers) eventually escaped or were rescued and formed a basis for the reconstitution of the medical units.