On March 8, 1806 Decatur married Susan Wheeler, noted for her beauty and intelligence and daughter of the mayor of Norfolk, Virginia, Luke Wheeler. Before marrying Susan he had already made vows to serve his country faithfully and honorably and felt to not do so would make him unworthy of her hand. Susan was once pursued by Vice President Aaron Burr and Jérôme Bonaparte, brother to Napoleon both of whom she had turned down.

Decatur's Naval career began when he was but a midshipman which took him through the Quasi - War with France, the First Barbary War, the War of 1812 and through another Barbary War at Algiers, along the shores of North Africa. In every theater of operation Decatur's service in the nation's young Navy was characterized with heroism and exceptional performance where he emerged as a national hero who ultimately came to be identified as the father of the post revolutionary American Navy.

At the age of 17 Decatur was employed at the shipbuilding firm of Gurney and Smith, acting as the company's supervisor to the early construction of the frigate United States. He later served as a Midshipman on board this vessel under Commodore John Barry. He was one of "Preble's Boys" and friends with Charles Stewart and Richard Somers.

Decatur saw service throughout the Quasi - War of 1798 to 1800, an undeclared naval war with France involving disputes over U.S. trading and shipping with Britain. When the American Revolution came to a close there were few American ships capable of defending the American coastline, much less of protecting American merchant ships at sea and abroad. What few ships that were available were converted into merchant ships. Now that America had won independence and no longer had the protection of Britain it was at once faced with the task of protecting her own ships and interests which were now being threatened by France in particular along with Barbary pirates of North Africa. The French were outraged that America was still involved with trading with Britain with whom they were at war and because of American refusal to pay a debt that was owed to the French crown, which had just been overthrown by the newly established French Republic. As a result France began intercepting American ships that were involved with trading with Britain.

On March 27, 1794, the U.S. Congress passed the 'Act to provide for a Naval Armament'. On July 8 President John Adams appointed Benjamin Stoddert as the first Secretary of the Navy. At this time there were no America naval commanders that could measure up to Decatur's performance and distinction, moreover, America was not even ranked with European naval forces.

In March of 1796, construction of new American frigates slowly progressed. However, because of a peace accord made with Algeria, construction on all six ships was halted. After some debate and at the insistence of George Washington, Congress passed an act on 20 April 1796 allowing the construction and funding to continue only on the three ships nearest to completion which at the time were USS United States, USS Constellation and the USS Constitution.

In 1798, following in the footsteps of his father, Stephen Decatur, Sr., commander of the USS Delaware at this time, Decatur’s good friend, veteran and hero in the revolutionary War, Captain John Barry, obtained Decatur's appointment as midshipman on the USS United States, under Barry’s command. Decatur accepted the appointment on May 1st. Decatur’s father was given command of Delaware, which sailed along with United States. To ensure his son’s success in his career, Decatur, Sr., hired a tutor, Talbot Hamilton, a former officer of the Royal Navy, to instruct his son in navigational and nautical sciences. He was promoted to the rank of Lieutenant in 1799. For a brief period, Decatur served aboard the sloop USS Norfolk but soon transferred back to the United States. Following the Quasi - War, the U.S. Navy underwent a significant reduction of active ships and officers; Decatur was one of the few selected to remain commissioned.

Upon the onset of the first Barbary War in 1801 Decatur was assigned to the frigate USS Essex as first lieutenant. Decatur's ship was attached to Commodore Richard Dale's squadron and sailed to the Mediterranean to confront with the Barbary states who were attacking American shipping, stealing cargoes and often holding crews for huge ransoms. After serving aboard USS New York, Decatur returned to the United States and took command of the new brig USS Argus. Sailing across the Atlantic to Gibraltar, he turned the ship over to Lieutenant Isaac Hull. Decatur was then given command of the USS Enterprise, a 12-gun schooner.

Enterprise and the frigate USS Constitution captured the Tripolitan ketch Mastico on December 23, 1803, after a close confrontation. After its capture the ketch was renamed Intrepid, and was given to Decatur for use in a daring raid to destroy the frigate USS Philadelphia which had run aground and been captured in Tripoli harbor in October. On February 16, 1804, at seven o'clock in the evening under the dim light of a new moon the Intrepid, disguised as a Maltese merchant ship and flying British colors, casually entered Tripoli harbor. Claiming that they had lost their anchors in a storm, Decatur asked permission to tie up alongside the captured frigate. By 9:30 the Intrepid was within 200 yards of the Philadelphia, whose lower yards were resting on the deck with its foremast cut away. The men were divided into groups, each one assigned to secure given areas of the Philadelphia, with the instruction to not use firearms unless absolutely necessary. When the two ships were close enough, Decatur stormed aboard Philadelphia with sixty men. Fighting with swords and pikes, they took control of the ship without losing a single man and began preparations to set it on fire. After Philadelphia was set ablaze and he was sure the fire had taken hold, Decatur was the last man to leave the burning ship. Decatur and his men successfully departed from the scene in Intrepid and while evading cannon fire from the harbor's defenses he reached the open sea. After hearing of Decatur's achievement, Vice Admiral Lord Horatio Nelson called it "the most bold and daring act of the age."

Upon the day of Decatur's return with the Intrepid Commodire Preble wrote to Stoddert, Secretary of the Navy, recommending Decatur be promoted to captain. Consequently in 1804 Decatur was promoted to captain at age twenty - five in recognition for his successful raid, making him the youngest ever to hold the rank. Decatur commanded the frigates Constitution and Congress for the duration of the war, before returning home in 1805. Decatur's daring and successful burning of the Philadelphia made Decatur an immediate national hero.

With the significant victory achieved at Tripoli with the burning of the Philadelphia, Preble now had reason to believe that bringing Tripoli to peaceful terms was in sight. Preble planned another attack on Tripoli and amassed a squadron, assigning a division of nine gunboats to Decatur. Preble in command of the Constitution along with the squadron began the bombarding of Tripoli on August 3, 1804, which lasted for three hours. The Tripolians inflicted considerable damage on some of the attacking vessels, Decatur's ship inflicted with a 24 pound shot through her hull. Before the battle ended the USS John Adams, commanded by Isaac Chauncey appeared on the scene. The vessel had on board Decatur's official documents promoting him to captain. The John Adams also brought news that, upon the loss of the Philadelphia, the government was sending four frigates, the President, the Congress, the Constellation and the Essex to Tripoli with enough force to convince the Bey of Tripoli that peace was his only viable alternative. Because Preble's command was not high enough for this advent the John Adams also brought the news that he would have to surrender command to Commodore Barron.

In 1807 Decatur was appointed commander of the Chesapeake upon the removal of her previous commander, Commodore Barron, following his court martial. Decatur was a member of the court martial that had found Barron guilty of unpreparedness. Barron's previous orders to sail for the Mediterranean were canceled and the Chesapeake was instead assigned to Commodore Decatur with a squadron of gunboats to guard the American southern coast.

In 1810, the Macedonian and the United States had been berthed next to one another in port at Norfolk, Virginia. The British captain John Carden wagered a beaver hat that if the two ever met in battle, the Macedonian would emerge victorious. However, the engagement in a heavy swell proved otherwise as the United States pounded the Macedonian into a dismasted wreck from long range. The Macedonian had no option but surrender, and thus was taken as a prize by Decatur. Eager to present the nation with a prize, Decatur spent a fortnight refitting the captured British frigate so as to make it able to travel back across the Atlantic.

After repairs, United States — accompanied by USS Macedonian and the Sloop of War USS Hornet — sailed from New York on 24 May 1813. On 1 June, the three vessels were driven into New London, Connecticut, by a powerful British squadron, and United States and Macedonian were kept blocked there until the end of the war.

Decatur attempted to sneak out of New London harbor at night in an effort to elude the British blockading squadron. While attempting to leave the Thames River Decatur saw blue lights burning near the mouth of the river in sight of the British blockaders. Convinced that these were signals to betray his plans he abandoned the project. Suspicion was directed against the "peace men" and the odious epithet of "Bluelight Federalists" long was applied to extreme Federalists. In the spring of 1814, Decatur transferred his commodore's pennant to the President (44), flagship of his new squadron consisting of Hornet (20), Peacock (22), and Tom Bowline (12). However, the British had established a strict blockade in the squadron's port of New York, therefore restricting any cruises.

In January 1815, Decatur's squadron was assigned a mission in the East Indies. Shortly thereafter, Decatur attempted to break through the blockade alone in the President and make for the appointed rendezvous at Tristan da Cunha. On January 15, a day after setting sail from New York, he encountered the British West Indies Squadron composed of Razee HMS Majestic (56 guns, Captain John Hayes) and the frigates HMS Endymion (40 guns, Captain Henry Hope), HMS Pomone (38 guns, Captain John Richard Lumley) and HMS Tenedos (38 guns, Captain Hyde Parker). After the President was accidentally run aground, Decatur continued to attempt to evade his pursuers. Endymion was the first to come up and after a fierce fight, he managed to disable the British frigate. But due to the damage sustained from Endymion, Decatur's frigate was finally overhauled by Pomone and Tenedos, causing him to surrender his command. However, his hail of surrender was not heard by Pomone, firing two broadsides into the President until she hauled down a light to signify surrender. As Decatur himself termed it, "my ship crippled, and more than a four - fold force opposed to me, without a chance of escape left, I deemed it my duty to surrender". Decatur's command suffered 24 men killed and 55 wounded, a fifth of his crew, including Decatur himself who was wounded by a large flying splinter.

Decatur and his men were transported as prisoners to Bermuda until February 1815. On February 8, with news of the cessation of hostilities, Decatur traveled aboard HMS Narcissus (32), landing in New London, Connecticut. On February 26, Decatur arrived in New York City, where he convalesced in a boarding house.

At War's end Decatur received a sword as a reward and thanks from Congress for his service in Tripoli and was also awarded the Gold medal for distinguished service in the War of 1812.

Now that war (of 1812) with Britain was over the United States could concentrate on pressing matters in the Mediterranean, at Algiers. American merchant ships and crews were being seized and held for large ransoms. On February 23, 1815, President Madison urged Congress to declare war. Congress approved and on March 2, declared war against Algiers. Madison had chosen Benjamin Williams Crowninshield as the new Secretary of the Navy. Because of Decatur's great successes in the War of 1812 Crowninshield chose him to command the lead Naval squadron to Algiers. Beginning 20 May 1815, Commodore Decatur in command of the USS Guerriere led a squadron of ten ships to the Mediterranean Sea to conduct the Second Barbary War, which would put an end to the international practice of paying tribute to the Barbary pirate states. Decatur, Commodore Bainbridge and William Shaler were appointed joint commissioners for negotiating terms of peace with Algiers and to secure the release of American slaves, to obtain an end to tribute, and finally, to procure favorable prize agreements.

Before committing himself to the Mediterranean Decatur learned from the American consuls at Cadiz and Tangier of any squadrons in the Atlantic, discovering that a squadron under the command of Reis Hammida had passed by into the Mediterranean, most likely off Cape de gat.. Decatur's squadron arrived at Gibraltar on 15 June 1815. This attracted much attention and prompted the departure of several dispatch vessels to warn Hammida of the squadron's arrival. Decatur's visit was brief with the counsul lasted only for as long as it took to communicate with a short letter to the Secretary of the Navy informing him of earlier weather problems and that he was about to "proceed in search of the enemy forthwith", where he at once set off in search of Hammida hoping to take him by surprise.

Capturing the Algerian fleet flagship the Battle off Cape Gata and the Mashouda as well as the Algerian brig Estedio which was en route to Algeria at the Battle off Cape Palos, Decatur secured an amount of levying power with which to bargain with the Dey of Algiers. Upon arrival, Decatur exhibited an early use of gunboat diplomacy on behalf of American interests. A new treaty was agreed to within 48 hours of his arrival, confirming the success of his objectives.

After bringing the government in Algiers to terms, Decatur's squadron set sail to Tunis and Tripoli to demand reimbursement for proceeds withheld by those governments during the War of 1812. With a similar show of force exhibited at Algiers Decatur received all of his demands and promptly sailed home victorious. For this campaign, he became known as "the Conqueror of the Barbary Pirates".

After his victory in the Mediterranean over the Barbary states who had terrorized and enslaved Christian merchants for centuries, Decatur returned to the United States, arriving at New York on November 12, 1815, with the brig Enterprise. He was met with a wide reception from dignitaries and countrymen. Among the more notable salutations was a letter Decatur received from the Secretary of State James Monroe that related the following tidings of appreciation:

"I take much interest in informing you that the result of this expedition, so
glorious to your country and honorable to yourself and the officers and men
under your command, has been very satisfactory to the President." - JM

The Secretary of the Navy, Benjamin W. Crowninshield, was equally gracious and thankful. Since a vacancy was about to occur in the board of Navy commissioners with the retirement of Commodore Isaac Hull, the Secretary was most anxious to offer the position to Decatur, which he gladly accepted. Upon his appointment Decatur made his journey to Washington, where he was again received with cordial receptions from various dignitaries and countrymen. He served as a Navy Commissioner from 1816 to 1820.

During his tenure as a Commissioner, Decatur became active in the Washington social scene. At one of his social gatherings, Decatur uttered an after dinner toast that would become famous: "Our Country! In her intercourse with foreign nations may she always be in the right; but right or wrong, our country!" Carl Schurz would later distill this phrase more famously as, "My country, right or wrong; if right, to be kept right; and if wrong, to be set right."

In 1818, in Washington, D.C., Decatur built a house designed by Benjamin Henry Latrobe. The Decatur House, now a museum, was located on President's Square (Lafayette Square), Washington, DC.

Decatur's illustrious life and distinguished service in the U.S. Navy came to an unfortunate end when in 1820, Commodore James Barron challenged Decatur to a duel, relating in part to comments Decatur had made over Barron's conduct in the Chesapeake - Leopard Affair of 1807. Decatur had served on the court martial that had found Barron guilty of unpreparedness, and had barred him from a command for the next five years. Because of Barron's loss of the Chesapeake to the British he was met with much criticism among fellow naval officers. Among them Decatur was one of the most outspoken. Barron's challenge to Decatur occurred during a period when duels between officers was so common that it was creating a shortage of experienced officers forcing the War Department to threaten to discharge those who attempted to pursue the practice.

Barron's second was Captain Jesse Elliott, known for his antagonism to Decatur. Decatur asked his supposed friend Commodore William Bainbridge to be his second, to which Bainbridge consented. However, Decatur made a poor choice: Bainbridge, who was five years his senior, had long been jealous of the younger and more famous Decatur. The conference between the two seconds lasted three - quarters of an hour. The duel was fought at Bladensburg Duelling Field in Bladensburg, Maryland (now in Colmar Manor, Maryland), on 22 March 1820. Just before the duel, Barron spoke to Decatur of conciliation; however, the men's seconds did not attempt to halt the proceedings.

The duel was arranged by Bainbridge with Elliott in a way that made the wounding or death of both duelists very likely. Both subjects would be standing in close proximity of each other face to face; There would be no back - to - back pacing away and turning to fire. The duelists were instructed by Baibridge, "I shall give the word quickly -- 'Present, one, two, three.' You are neither to fire before the word 'one', nor after the word 'three'. After taking their positions each duelist raised his pistol, cocked the flintlock and while taking aim stood in silence. Bainbridge called out, 'One', Decatur and Barron both firing before the count of 'two'. Decatur's shot hit Barron in the lower abdomen which ricocheted into his thigh. Barron's shot hit Decatur in the pelvic area, severing arteries. Both of the duelists fell almost at the same instant, Decatur, mortally wounded, clutching his side, exclaimed "Oh, Lord, I am a dead man". Lying wounded Commodore Barron (who, ultimately survived) declared that the duel was carried out properly and honorably and told Decatur that he forgave him from the bottom of his heart.Decatur was carried back to his home on Lafayette Square, where he died at approximately 10:30 p.m. that night. While wounded, he is said to have cried out, "I did not know that any man could suffer such pain!"

Washington and the nation were shocked when Decatur was killed at the age of forty - one in a duel with a rival navy captain. Although he died at a relatively young age, Decatur helped in the direction the nation would go and played a significant role establishing the new nation’s identity.

Stephen Decatur's funeral was attended by Washington's elite, including President James Monroe and the justices of the Supreme Court, as well as most of Congress. Over 10,000 citizens of Washington attended to pay their last respects to a national hero. The Marines led Decatur's funeral procession some of whom would be the firing party, while its band played a mournful dirge. Following were Naval Officers and Seamen. At the funeral service a grieving seamen proclaimed, "He was the friend of the flag, the sailor's friend; the navy has lost its mainmast". Stephen Decatur died childless. Though he left his widow $75,000, a fortune at the time, she died penniless in 1860.

Decatur's remains were temporarily placed in the tomb of Joel Barlow at Washington, but later moved to Philadelphia, where they were interred at St. Peter's Church, along side his mother and father.

For his heroism in the Barbary Wars and the War of 1812 Decatur emerged as an icon of American Naval history and was roundly admired by most of his contemporaries as well as the citizenry.

• Five U.S. Navy ships have been named USS Decatur in his honor.
• An engraved portrait of Decatur appears on Stephen Decatur as depicted on a 1886 Silver Certificate on series 1886 $20 silver certificates.
• Stephen Decatur's home in Washington, D.C. is a museum owned by the National Trust for Historic Preservation.
• At least 46 communities in the United States have been named after Stephen Decatur.