Commanded by Major General William "Bill" Slim, it landed in Basra in April, moving up the Euphrates and capturing Baghdad and the oilfields of Mosul as part of the Anglo-Iraqi War. When Iraq's ally Nazi Germany relocated its aircraft to Vichy French Syria, the 10th invaded Syria from Iraq in June. The 21st Brigade advanced towards Aleppo, while the 20th and 25th Brigades guarded the communication lines and the Mosul oilfield respectively.