The division was initially responsible for the governorates (roughly provinces) of Al Muthanna, Maysan, Basra, and Dhi Qar.

In the aftermath of the 2003 invasion of Iraq, which had the British codename 'Operation Telic,' the British 1st Armoured Division[2] and 3rd Mechanised Division[3] were successively responsible for the command and control of the occupation forces in south east Iraq.

After the 3rd Mechanised Division's tour of duty came to an end it was replaced by a composite headquarters still known as MND (SE).

[7] In the months following the end of the invasion, the division expanded to include UK, Dutch, Norwegian, Italian, Japanese, Australian, NZ, Romanian, Danish, Portuguese, Czech and Lithuanian troops.

As of February 2007, the Australians, Romanians, Danes, Czechs and Lithuanians remain (see Multinational Force in Iraq for further information).