In 1839 the British learned that Russia was planning an invasion of the Khanate of Khiva. In December 1839 acting Captain Abbott was sent from Herat to Khiva in an attempt to negotiate the release of Russian slaves and thereby deny the Russians a pretext for invasion. If war had already broken out, Abbott was instructed to attempt to negotiate a settlement. Abbott reached Khiva in late January, a week or so before the Russians were forced to turn back due to an unusually cold winter. The Khivans knew little of Britain and he was hampered by a lack of understanding of Khivan language and culture. The attempt to release Russian slaves failed. He did agree with the Khivan ruler, Allah Quli Khan, to establish a British agent in Khiva and to travel to Russia to negotiate between the two powers. He had no authorisation to serve as the Khan's agent, but had no way to communicate with his superiors in India. In March 1840 Abbott set off from Khiva to Fort Alexandrovsk on the Caspian Sea. His caravan was attacked by Kazakhs and he was wounded in the hand and taken hostage, but he and his party were released because they feared retribution. He reached St Petersburg but the attempt at mediation failed. His bravery was recognised through promotion to full Captain.