After her first six-month tour of duty in Basra, Iraq in 2008, she returned to the United Kingdom and qualified as a Class One medic.
[citation needed] In 2010, Watson was on her first tour as a fully qualified battlefield medic, serving alongside 9 Platoon, C Company, 1st Battalion, the Duke of Lancaster's Regiment, based mostly at Checkpoint Azadie in Helmand Province, Afghanistan.
An Afghan National Army (ANA) soldier, about 70 metres (230 ft) ahead of Watson, received two bullet wounds in the pelvis.
Watson ran forward under heavy fire to take over but his Afghan comrades tried to stop her because they did not want a woman to treat him.
[citation needed] On another patrol, Watson put herself in "mortal danger" to attend to a wounded Afghan soldier while under heavy Taliban fire.