British forces in southern Iraq will come under American command from Tuesday, as they begin their planned withdrawal from the country.
Most of the British troops are due to leave by the end of May.
The handover marks the end of Britain's military presence in Iraq and the main base near the city of Basra is taking on an increasingly American flavour.
United States soldiers are now a visible presence, with British troops handing over many of the buildings and duties at the camp as they pack up after six years in Iraq.
From Tuesday a US general will be in command of coalition forces in the south.
However, the US role in Iraq will be different, focusing more on training Iraqi police as well as keeping open the supply route between the south and the capital Baghdad.