He entered the English army, and in 1811, as aide-de-camp to the duke of Wellington, took part in several campaigns of the Peninsula War.
The Rhodian navy, which had distinguished itself in most of these wars, did further good service on behalf of Pompey in his campaigns against the pirates and against Julius Caesar.
In the early days of the Republican party, when the shameful scenes of the Kansas struggle were exciting the whole country, and during the campaigns of 1857 and 1858, he became known as an effective speaker and ardent anti-slavery man.
By that monarch he was made colonel of horse, and in that capacity served in the campaigns during the early part of the reign.
The landing of Coote preserved Madras from destruction, though the war lasted through many campaigns and only terminated with the death of Hyder.