He joined the navy in April 1766, as a volunteer aboard his father's ship and spent most of his early service in the Mediterranean, in the frigates of the Toulon Fleet.

When France entered the American Revolutionary War, Missiessy joined the 64-gun Vaillant in Admiral d'Estaing's fleet, where he took part in the initial engagements off Newport, St Lucia and Grenada, and in September 1779, the failed attack on Savannah.

The Rochefort squadron was intended to rendezvous with Villeneuve's fleet in the West Indies and draw British ships there, before racing back across the Atlantic and seizing control of the English Channel.

Missiessy was promoted to enseigne de vaisseau in April 1777 and joined Sultane for an expedition to the Barbary Coast, where he helped prevent attacks on French shipping by corsairs.

Aboard the 64-gun Vaillant, Missiessy participated in initial engagements off Newport, St Lucia and Grenada, and in September 1779 took part in the failed attack on Savannah.

[4] In June 1801, Missiessy's old commander, Truget, requested him as his Chief of Staff for the combined French and Spanish fleet stationed at Cadiz but when peace was declared in March 1802, he was ordered back to Paris and made Maritime Prefect.

[4] The Rochefort squadron was a key element in Napoleon's planned invasion of the United Kingdom; intended to rendezvous with Villeneuve's fleet in the West Indies and draw British ships there, before racing back across the Atlantic and seizing control of the English Channel.

[5] Aboard the five ships-of-the-line, three frigates and two corvettes were 3500 troops under General Joseph Lagrange and artillery, supplies and weapons to reinforce the French garrisons of Martinique and Guadeloupe.

[5] The approach to Martinique was guarded by a British battery mounted on Diamond Rock, forcing visiting ships to make a long detour through unfavourable open sea with strong winds and currents.

Between 5 and 10 March Missiessy's force attacked the British colonies of St Kitts, Nevis and Montserrat, collecting £25,000 in ransom money in the process.

Despite carrying out his orders in full, Missiessy was made a scapegoat for Pierre-Charles Villeneuve's failings and lambasted by Napoleon for not recapturing Diamond Rock.

[6] In February 1808, having been unemployed since his return from the West Indies, Missiessy was given command of the Scheldt squadron and successfully defended Antwerp from the British attacks that occurred between July and September 1809, part of the ill-fated Walcheren Campaign.

Having already been promoted Vice-Admiral on 9 March, he was rewarded for his efforts with appointment to Commander-in-Chief of the Northern Coasts and made a Count of the Empire on 23 February 1811, the latter position coming with an annuity of 20,000 francs.