page_title: Portuguese conquest of French Guiana
section_title: Invasion
hierarchical_section_title: Portuguese conquest of French Guiana / Invasion
caption_attribution_description: English: A map from 1760 depicting the fortifications of the town of Cayenne in French Guiana.
context_page_description: The Portuguese conquest of French Guiana was an 1809 military operation against Cayenne, capital of the South American colony of French Guiana, in the scope of the Napoleonic Wars. The operation was performed by a combined expeditionary force that included Portuguese and British military contingents.
  The operation was part of a series of attacks on French-held territory in the Americas during 1809 and due to commitments elsewhere, the British Royal Navy was unable to send substantial forces to attack the fortified river port. Instead, appeals were made to the Portuguese government, which had been driven out of Portugal the year before during the Peninsular War and was resident in Brazil. In exchange for providing troops and transports for the operation, the Portuguese were promised Guiana as an expansion of their holdings in Brazil for the duration of the conflict.
  The British contribution was small, consisting solely of the minor warship HMS Confiance. Confiance however had a highly effective crew and an experienced captain in James Lucas Yeo, who was to command the entire expedition.
context_section_description: The town of Cayenne is situated on an island in the mouth of the Cayenne and Mahury Rivers. In 1809, its approaches were protected by a series of forts and gun batteries, while the town itself was dominated by a modern star fort. Acknowledging that his force was not large enough to invade the island directly, Yeo decided instead to attack a series of outlying forts on the Mahury River in an effort to draw out the French defenders. On 6 January 1809, preparations were complete and Yeo launched an attack during the night, landing at Pointe Mahury at 03:00 on 7 January in five canoes despite heavy rains, which continued throughout the campaign. The surf was strong and all five canoes were wrecked on the beach, but there were no casualties. Yeo detached a Portuguese force under Major Joaquim Manuel Pinto against the Dégras de Cannes battery while he advanced on Fort Diamant with a force of seamen and marines. Both positions were rapidly carried, the British suffering seven men wounded to French losses of six killed and four wounded. Four cannons were seized, as were 90 French soldiers. Both fortifications were then garrisoned with soldiers from the squadron.
  With the capture of the Mahury forts, the French in Cayenne risked being cut off from external help and besieged. In response, Governor Victor Hugues mustered most of the 600 troops available to him and marched on the Allied positions. Consolidating his forces at Dégras de Cannes, Yeo demolished Fort Diamant and sent scouts down river, where two further forts were discovered at Trio and the Canal de Torcy. The latter fort had been constructed to defend the approaches to Hugues' residence, which was situated on the canal. Yeo immediately ordered the Portuguese cutters Leão and Vingança into the river to attack the forts, the Portuguese bombarding the positions for an hour while Yeo prepared assault forces. Yeo himself led the attack on the Trio fort while a Portuguese party attacked the fort on the canal. Both positions were captured and their 50 strong garrisons driven off.
  As Yeo secured his position from attack from the river, Hugues arrived at Dégras de Cannes. Despite attacking Lieutenant Colonel Marques' garrison immediately, Hugues was unable to defeat the Portuguese before Yeo returned, and was forced to retreat after a three-hour engagement. A secondary force sent against Fort Diamant saw the British demolition party on the walls and, assuming the garrison there to be larger than expected, retreated without an assault. The following morning, as Hugues fell back on his residence, Yeo followed, using the river and canal to close with the position. Hugues had fortified his property with 100 men and two artillery pieces, and ordered his men to fire on a party of British sailors offering a truce. A second attempt was met with cannon fire, and although a third attempt via one of Hugues' slaves drew a response, the French general's overtures were only an attempt to stall the Allies while his men laid an ambush in the trees near their landing point.
  At a signal from one of the artillery pieces, the French ambush party began a heavy fire on the troops advancing up the lane towards the house. Charging forward, Yeo led an attack on the ambushers at the head of his men and in hand-to-hand fighting seized the house and its artillery. Gathering his forces, Yeo then marched on Cayenne, expecting to meet Hugues at the Beauregard plain, where the French general had stationed his remaining 400 men. Reaching the position on 10 January, Yeo sent two junior officers into Cayenne offering an armistice, which was accepted, Hugues recognising that he was outnumbered and outmanoeuvred. Over the next four days, Yeo's men took the surrender of the outlying French garrisons and units, with the entrance to Cayenne planned for 14 January.
caption: Map of the fortifications at Cayenne, made in 1760
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