Their work during the retreat was done under difficulties. There were alarms at Compiegne of Uhlans seen in the vicinity of the aerodrome, and a guard was provided from the Camerons. Major B. H. Barrington-Kennett remarks on the difficulty of defending a Flying Corps camp from attack by cavalry. It would seem advisable, he says, when camped in an open aerodrome to park the aeroplanes inside a laager formed by lorries and cars. The head-lights of the cars would lighten a good field of fire, and would probably, if switched on at the approach of cavalry, cause the horses to stampede. The Royal Flying Corps, he adds, should be armed and practised with machine-guns and rifles, so that they may protect themselves without asking for an escort. At Juilly on the 1st of September there was another alarm. The country to the north was thickly wooded, and German cavalry, which proved later to be those escaped from the affair at Nery, were reported within a few miles, with no British troops between. General Headquarters at Dammartin-en-Goele, some two miles away, hastily took their departure, and the Royal Flying Corps transport was sent off at once to Serris. But the aeroplanes could not leave, for already it was dark. The suggestion was made that the aeroplanes should fly off in the dark, but fortunately, says Major C. J. Burke, this was not attempted. The Flying Corps stood to arms to defend itself. A sunken road running east and west past the aerodrome was occupied, rifles and ammunition were served out to the mechanics, and machine-guns were set in position. After a time a troop of North Irish Horse arrived, to aid in the defence. All night watch was kept, but the German cavalry did not appear. In the morning, for the first time since the beginning of the retreat, there was no ground mist, and the machines got away at once.