The 99th was initially transferred to Perham Dows Camp, located between the towns of Andower and Salisbury. Training started immediately. First regular infantry training, long marches, survival training, weaponry, obstacle courses and everything else that could be thrown on an elite unit. This included daily 20 mile hikes in the Dartmoor forest for 15 days with full gear. Weapon training included operation and maintenance of both .30 and .50 caliber machine guns.
In the middle of January 1944, the 99th Battalion was transferred to Wales, where the battalion was quartered in Nissen huts on the property which surrounded the old, romantic, Glenusk Castle. The officers and clerical staff lived in the castle itself. The nearest town was Crickhowell, and the picturesque town, Abergavenny was nearby. The first view of Glenusk Park was not very encouraging. The mud was 20 - 30 cm (8-12inches) deep, and the previous occupants had been ordinary sheep, so the first night was not the best. But after a couple of days spent with rolled up shirt sleeves, buckets, hammer and nails, and lots of goodwill, you couldn't recognize the huts. The 99th probably experienced its happiest time in the British Isles, here in Glenusk Park, Wales. During this time, members of the Battalion often went to London on leave.
End of April 1944, it became clear that an invasion of the European continent was eminent as the Battalion was transferred to Lodlow Bivouac Area. Here they were quartered in 8 men tents and the rumors were that an invasion was to follow very shortly. On the 6th June 1944, the message was received that the invasion was underway.