In 1780, Howe lost in his bid to be re-elected to the House of Commons. In 1782, he was named lieutenant general of the ordnance and appointed to the Privy Council. His colonelcy was transferred from the 23rd Fusiliers to the 19th Light Dragoons in 1786. He resumed limited active duty in 1789, when a crisis with Spain over territorial claims in northwestern North America threatened to boil over into war. He was placed in command of the forces organized for action against Spain, but the crisis was resolved and Howe did not see further action until 1793, when the French Revolutionary Wars involved Britain. He was promoted to full general in 1793, and commanded Northern District from 1793 and Eastern District from 1795. In 1795, he was appointed governor of Berwick-on-Tweed. When his brother Richard died in 1799 without surviving male issue, Howe inherited the Irish titles and became the 5th Viscount Howe and Baron Glenawley. In 1803, he resigned as lieutenant general of the ordnance, citing poor health. In 1808, he was appointed governor of Plymouth. He died at Twickenham in 1814 after a long illness. Howe had married Frances Connolly, often referred to as Fanny, in 1765. Their marriage was childless. Therefore, his titles died with him. His wife survived him by three years. Both are buried in Holly Road Garden of Rest, Twickenham.