YSAMBERT, Gustave (ee-zahm-bair), French naval officer, born in Brittany in 1667; died in Rio Janeiro, Brazil, 18 March, 1711. After commanding a privateer in the West Indies and the Pacific ocean, he entered the royal navy about 1700, with the rank of commander. In 1710 he sailed as chief-of-staff of Jean Baptiste Duclerc in the latter's expedition to Brazil. On 6 August they sighted Rio Janeiro, which they could have then carried by a speedy attack, but, Duclerc's intention being opposed by Ysambert and the council of war, they anchored on 17 August at a point near Tejuco and landed 900 marines. The Portuguese meanwhile had prepared for resistance, and when the French arrived at Nero Engenho dos Padres da Companhia, six miles from Rio Janeiro, they met a Portuguese division which they defeated. Failing to receive co-operation from the fleet, which had been dispersed by a tempest, they were attacked, on 18 September, by the viceroy, Francisco de Castro Moraes, with superior forces, but routed him and followed the fugitives into the city. Being received there by a cross-fire from fortified buildings, Ysambert with a small party barricaded himself in the city-hall, while Duclerc took shelter in the customhouse. After a heavy loss, Duclerc agreed to capitulate on condition that his forces should be returned to France; but Ysambert, whose position was stronger, was reluctant to trust the Portuguese, and continued resistance till he received peremptory orders from Duclerc to comply with the terms of the capitulation. The leaders were well treated, but a few days later the French fleet, unaware of the surrender, made an attack on the city. The viceroy proclaimed the capitulation violated, and the officers were thereafter kept in close confinement. Duclerc and Ysambert were killed by the guard in an attempt to escape, or murdered, according to other historians, on 18 March, 1711. Their death was avenged a few months later by Dugay-Trouin, who released the surviving French prisoners.