The action of 21 April 1806 was a minor engagement between a French frigate and British forces off South Africa during the Napoleonic Wars. The Île Bonaparte and Île de France constituted French outposts in the Indian Ocean, from which privateers and frigate squadrons could engage in commerce raiding and disrupt British shipping. After encountering a strongly escorted British convoy, the 40-gun Cannonière attempted to flee, but was rejoined by the 74-gun HMS Tremendous. In the ensuing battle, Captain Bourayne displayed superior sailmanship and managed to fend off his much stronger opponent by a combination of manoeuvers that rendered the batteries of Tremendous ineffective, and threatened her with sustaining raking fire. The French frigate thus managed to evade and escape.