[2] Saumarez was born at Saint Peter Port, Guernsey,[3] to an old island family, the eldest son of Matthew de Sausmarez (1718–1778) and his second wife Carteret, daughter of James Le Marchant.

After forty-seven engagements, unfortunately he had to run Spitfire ashore and burn her on 30 July 1778 when a French fleet under Admiral d'Estaing arrived at Narrangansett Bay.

[8] While commanding HMS Russell (74 guns), Saumarez contributed to Rodney's victory over de Grasse at the Battle of the Saintes on 12 April 1782.

[9] In reward, Saumarez was knighted by King George III[10] and given a presentation plate by the City of London, although he later received a bill for £103 6s 8d (equivalent to £15,300 in 2023), from a Mr. Cooke for "the honour of a knighthood".

Saumarez refused to pay, telling Cooke to charge whoever had paid for Edward Pellew's knighthood after his successful action.

The French squadron outgunned the British by 192 guns to 92, but Saumarez succeeded in getting his frigates to safety by sailing between rocks on the west coast of Guernsey and around the island to the St Peter Port anchorage.

[3] Orion was one of the ships sent to reinforce Sir John Jervis in February 1797, when Saumarez distinguished himself in the Battle of Cape St. Vincent.

During the early stages he helped repel a sustained attack on the British line and covered the retreat of HMS Colossus when she was forced to retire from the action.

Later, when the engagement had turned to a general melee, Saumarez forced the Salvador del Mundo to surrender before attacking the Santissima Trinidad with the help of HMS Excellent.

[3][13] On his return from Egypt Saumarez received the command of HMS Caesar, of 80 guns, with orders to watch the French fleet off Brest during the winters of 1799 and 1800.

In 1801 he was promoted to the rank of Rear-Admiral of the Blue, was created a baronet,[3] and received the command of a small squadron which was to watch the movements of the Spanish fleet at Cadiz.

When the French squadron, reinforced by Spanish ships sent from Cádiz, made to leave the bay, Saumarez, although substantially outnumbered, went in pursuit.

[17] During the Peace of Amiens, 1802–3, Saumarez remained at home with his family in Guernsey, and when war broke out again he was given command of the naval forces defending the Channel Islands.

[20] Saumarez's mission was to protect the British trade which was of vital importance for Royal Navy supplies and to blockade enemy ports such as those under French control in northern Germany.

[21] In 1812 Napoleon invaded Russia with half a million troops and Saumarez's fleet was instrumental in hampering French operations.

[23] The public bar at the Duke of Normandie Hotel in Saint Peter Port was named after Saumarez and features a portrait of him.

[13] After the Battle of the Nile, while in conversation with Nelson, on the quarterdeck of HMS Vanguard, Saumarez suggested that the tactic of doubling the French line had been a dangerous one as it exposed British ships to 'friendly fire'.

[13] Later Nelson wrote a letter saying, "I could have formed no opinion of Orion that was not favourable to her gallant and excellent commander [Saumarez] and crew".

In Treachery (2008) (US title The Privateer's Revenge) by Julian Stockwin, Saumerez's purported orders (actually a forgery) result in the disgrace of Thomas Kydd.