Waters served throughout the Peninsular War, being present at Talavera, Bussaco, Ciudad Rodrigo, Badajoz, Salamanca, Vittoria, the battle of the Pyrenees (during which he was wounded while speaking to Wellington), the Nivelle and Nive, Orthes and Toulouse. At Badajoz and Salamanca he acted as adjutant-general, and was mentioned in Wellington's Salamanca despatch. He received the gold cross with four clasps, and was made C.B. in 1815.