He entered the British Army in 1804 and was commissioned as ensign into the 3rd Foot Guards. Bowater was present in the Battle of Copenhagen (1807) and was then transferred with his regiment to Portugal. He joined the Taking of Porto and following the Battle of Talavera, where he was wounded, he purchased a lieutenancy in August 1809. In December he left for England, however returned to the Peninsular War after two years. He fought in the Battle of Salamanca in July 1812 and the Siege of Burgos in October. In the following year Bowater took part in the Battle of Vitoria in June and then was commanded to the Siege of San Sebastián until September 1813. A month later, he served in the Battle of the Bidassoa and in December was involved in the fightings of the Battle of the Nive.