 A native Frenchman, Sengle, then Bailli of the French langue of the Order, was heavily involved in the battles of the Knights in the Mediterranean and in North Africa against the Ottoman corsairs led by admiral Turgut Reis, and particularly in the struggles for Djerba and Tripoli.Sengle had considerable impact on the military strengthening of Malta, notably by initiating in 1554 the development of the city of Senglea, which was later named after him and uses his coat of arms.He also expanded Fort Saint Michael into a major bastion and completed Fort Saint Elmo, which had been begun by his predecessor, Grand Master Juan de Homedes y Coscon.