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War of the Austrian Succession: Siege of Louisbourg (1745)


War of the Austrian Succession: Siege of Louisbourg (1745)

Siege of Louisbourg, 1745

Photograph Source: Public Domain

Siege of Louisbourg - Conflict & Dates:

The Siege of Louisbourg was conducted from May 11 to June 28, 1745, during the War of the Austrian Succession (1740-1748).

Armies & Commanders


  • William Pepperrell
  • Commodore Peter Warren
  • 4,200 men
  • 90 ships


  • Louis Du Pont Duchambon
  • Pierre Morpain
  • 1,800 men

  • Siege of Louisbourg - Background:

    Beginning in 1739, the War of Jenkins' Ear saw Britain clash with Spain. This conflict was soon drawn into the larger War of the Austrian Succession which was raging on the Continent. As a result, by 1744 Britain also found itself at war with France. In the North American colonies, this larger conflict became known as King George's War and colonists on both sides began mobilizing. Striking first, French forces from the fortress city of Louisbourg on Île-Royale (Cape Breton Island) attacked the British fishing outpost of Canso. Striking on May 23, Captain François du Pont Duvivier's forces quickly overwhelmed Captain Patrick Heron's small garrison.

    Taken back to Louisbourg, the British prisoners were given freedom to wander the city before being repatriated to Boston. During this time, many of the officers took careful notes regarding Louisbourg's defenses and garrison. While noting that the city's seaward defenses were formidable, they found that nearby ridges and hills commanded the landward walls. Though his forces had won a victory at Canso, Governor Louis Du Pont Duchambon was increasingly concerned regarding the morale of his men. This was largely due to their pay being badly in arrears and the unfair distribution of loot from the Canso raid. Following a mutiny in December 1744, Duchambon was able to obtain some pay and additional supplies for his men.

    Siege of Louisbourg - The British Plan:

    In Boston, the Governor of the Province of Massachusetts, William Shirley, was becoming increasingly concerned regarding the military situation to the north. With the loss of Canso, Annapolis Royal became the only remaining British outpost in Nova Scotia. Eager to prevent its fall due to the risk of the French moving down the coast towards Boston, he sent 200 men to reinforce its garrison during the summer. Though the settlement repulsed French and Native American attacks later in the year, Shirley began seeking support for an expedition against Louisbourg. If successful, it would remove the French threat from the region as well as eliminate the threat posed by privateers that used the city as a base.

    Rallying support in the northern colonies, Shirley used the intelligence provided by the Canso prisoners to show that despite its reputation as a bastion, Louisbourg was weak. This ultimately proved successful as New Hampshire and Connecticut provided additional men while Pennsylvania, New York, New Jersey, and Rhode Island contributed ships, artillery, and funding. Assembling, command of the expedition was given to Kittery merchant William Pepperrell while the colonial naval force was overseen by Captain Edward Tyng. To support the operation, Shirley requested assistance from the Commodore Peter Warren who commanded the Royal Navy's West Indies Station. Warren agreed to come north as his orders directed him to protect the New England fisheries and strike at the French.

    Siege of Louisbourg - The Expedition Sails:

    Embarking around 4,200 men, Pepperrell moved up the coast and established a new base at Canso. While the colonial ships began a loose blockade of Louisbourg, they were hampered by winter ice in the nearby waters. Taking time to train his troops, Pepperrell was joined at Canso by Warren's squadron in early May. Coinciding with the Royal Navy's arrival, the colonial forces conducted a successful attack on Port Toulouse and other nearby French villages. Re-embarking his men, Pepperrell and Warren advanced on Louisbourg. Landing at Gabarus Bay on May 11, the colonial forces were confronted by a small French force led by Captain Pierre Morpain. This was soon swept aside and Pepperrell began advancing on the city.

    Siege of Louisbourg - Tightening the Noose:

    Moving forward in a disorganized fashion, the colonial forces soon occupied positions on the hills overlooking the city. Two days later, colonial troops, led by William Vaughan, occupied the Royal Battery, an outlying fortification, which had been abandoned by the French. Turning the battery's guns, they soon were used to batter the city's walls. As work began on siege lines, Pepperrell had additional artillery landed at Freshwater Cove. Due to the marshy nature of the terrain, they were transported to the siege on specially built sledges designed by Lieutenant Colonel Nathaniel Meserve of New Hampshire. By May 15, the first colonial batteries were in place and opened fire on Louisbourg.

    On May 31, the French warship Vigilante arrived off Louisbourg with reinforcements and supplies. Confronted by the British squadron, it was soon captured. With the artillery slowly opening breaches in the city's walls, Pepperrell began seeking a way to capture the batteries that defended the harbor so that Warren could join in a joint-attack against the garrison. On June 6, colonial forces attempted to storm the Island Battery in the harbor but were turned back with heavy losses. Reassessing the situation, the colonials began building a battery on Lighthouse Point. This position commanded the Island Battery and on June 24 British mortars effectively silenced the French guns.

    Two days later, with Louisbourg's walls breached and the British fleet massing to enter the harbor, Duchambon requested surrender terms. After brief negotiations, the French were permitted to march from the city with the honors of war while the inhabitants were be repatriated to France with their movable property. This last term angered many in the colonial ranks as they had been promised loot as part of their service in the expedition. Entering Louisbourg on June 28, colonial forces took possession of the French fortress. While the majority of the colonial troops desired to return home, around 2,000 were forced to serve as a garrison until British regulars arrived the following year.

    Siege of Louisbourg - Aftermath:

    The Siege of Louisbourg cost Pepperrell around 100 killed and wounded. Due to the harsh conditions of the area, over 500 more died during the fall and winter as colonial forces served garrison duty. French losses during the siege totaled around 50 killed and wounded as well as the remainder of the garrison captured. The victory at Louisbourg was extremely well-received in London and showed the government that the colonies were capable of mounting large operations without major support from abroad. For their efforts, Warren was promoted to rear admiral while Pepperrell was elevated to baronet and made colonel of a new regiment. Stunned by the city's loss, the French mounted the Duc d'Anville Expedition in 1746 to recover Louisbourg and the surrounding region. This came to nothing due to storms at sea and British attacks that prevented it from reaching its target.

    In 1748, colonial administrators were outraged when Louisbourg was returned to France as part of the Treaty of Aix-la-Chapelle. Their arguments that the city would again become a threat were proven true during the French & Indian War. As a result, a British force led by Major General Jeffery Amherst arrived in 1758 and conducted another successful siege of the city. In the wake of this victory, British engineers destroyed the city's walls lest it be returned to France again. The fall of Louisbourg in 1758 opened the way for Major General James Wolfe's attack on Quebec the following year.

    Selected Sources

  • Order of Patriots and Founders of America: Siege of Louisbourg
  • HistoryNet: Siege of Louisbourg
  • Battle of Louisbourg

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