When war broke out between the British and Turkish empires in 1914, the 6th (Poona) Division sailed from India to Basra to bolster Britain's allies, deny the port to enemy shipping, and secure Britain's Persian oil supplies. Further expansion followed: the capture of Al-Amara was the British Army's greatest victory of 1915. When an advance on Baghdad was repulsed, the Siege of Kut became the British Army's longest siege and greatest surrender.