In September 1788 Medows received the posts of Governor of Bombay and commander-in-chief of the Bombay Army. He remained there until January 1790, when he was transferred to become Governor of Madras and commander-in-chief of the Madras Army. A war with Tipu Sultan, Hyder Ali's son and successor as sultan of Mysore, had arisen, and Lord Cornwallis, the governor-general, now instructed Medows to open the campaign. Starting from Trichinopoli at the head of 15,000 men on 15 June 1790, Medows crossed the frontier into Mysore, and advanced in a westerly direction. On 22 July the army arrived at Coimbatore, which was found evacuated by the enemy. While he was able to secure the district, he spread his forces too thinly, and Tipu counterattacked against the smaller detachments, and Medows was forced to withdraw his forces to a few strong points in late 1790.