Desertion was the abandonment of one's post. Constance Clarke told the Sixth Doctor that she had no intention of deserting World War II and would return after her travels. (AUDIO: Criss-Cross)
The Were Lords, a species of soldiers created by the Time Lords of Gallifrey to fight in Vampire Wars, deserted from the war and settled in Greece on Earth in 1500 BC. (AUDIO: Brightly Shone The Moon That Night)