rawing was an essential part of 18c military training, particularly for engineers and surveyors. The British Army had employed drawing masters from the late eighteenth century at the Royal Military Academy, Woolwich, the Engineers College at Chatham, and the Military College at High Wycombe. Many soldiers were highly accomplished draughtsmen, producing clear and competent analyses of the Indian terrain, buildings and fortifications, just as Paul Sandby had done for the English Government's military survey of Scotland, which followed Prince Charles Edward's disastrous campaign in 1745 to regain the Scottish crown.

After successive Mysore Wars, vast tracts of land in India passed to the British, and by the end of the 18 century, there were insufficient British engineer officers to undertake all the related survey work. The Government therefore established a Survey School at Madras in 1794 to train Indian civilians. These men were often the sons of British soldiers and Indian mothers .

Allan actively served in the Fourth Mysore War, as Deputy Quartermaster General. He spoke Persian fluently and was therefore appointed to carry the flag of truce into the Palace after the fall of Seringapatam and offer cowle (right of passage) to Tipu and his family if Tipu himself immediately surrendered. Allan was also with Baird when Tipu's body was later found near the Water Gate, and his efficient, almost clinical records of the fortifications captures the atmosphere of the lull before the storm. Allan's watercolour of the attack itself was the source for a popular aquatint dedicated to David Baird, who had led the British out of the trenches on 4th May 1799.

Not long after this, Allan left India. In 1800, he was in London where Seringapatam, and anything associated with it, was a topic of great public - and therefore commercial - interest. Artists who had never been to India sought authentic references and images upon which to base their own versions of the Mysore drama. One such artist, the young J.M.W. Turner, must have been familiar with watercolours such as Allan's when he made his own studies of the Storming of Seringapatam, c.1800.