No exact record of his birth date exists, but it is believed he was relatively old at the time of his death. He was born to a respected military family in Anjou and was Lord of La Suze and Briollay, France, by birth right. He died sometime during January 1193. He was succeeded in Anjou by his daughter Margaret de Sablé, who by marriage passed the entire honor to William des Roches, also a knight of the Third Crusade. Robert did have an elder son, Geoffrey de Cornillé, but it is unclear as to why he did not receive the Sablé barony.
Despite only having a short tenure, de Sable's reign was filled with campaigning, and successful campaigning at that. The collective might of Richard the Lion Heart's strategy, Philip II Augustus's seasoned troops and the elite Templar knights scored many victories. During the 3rd Crusade, they laid siege to the city of Acre, which soon fell. Throughout August 1191, they also recaptured many fortresses and cities along the Palestinian coast, which had been lost previously.
The new coalition's finest hour was the Battle of Arsuf, September 7th 1191. Saladin's Muslim forces appeared to have become far stronger than the Christians, and a decisive victory was desperately needed. Pooling all of the crusader's strength, the Knights Hospitaller joined the ranks, plus many knights from de Sable's native Anjou, Maine, and Brittany. They met Saladin's troops on the dry plains and soon broke his ranks. Those who stayed to fight were killed, and the remaining Islamic troops were forced to retreat.
Acquisition of Cyprus
At the end of 1191, Richard Lion Heart agreed to sell Cyprus to the Templars for 25,000 pieces of silver. Richard had plundered the Island from the Byzantine forces of a rival Emperor in Cyprus some months earlier and had no real use for it. Whereas the Hospitallers would later establish solid bases in Rhodes and Malta, de Sable failed to do the same with Cyprus. He was Lord for 2 years, until he gave (or sold) the island to Guy de Lusignan, King of Jerusalem, as he was without a Kingdom.
De Sable did manage to establish a Chieftain House of the Order in Saint-Jean d’Acre, which remained for almost a century.
De Sable was lucky to have been Grand Master at all, as at the time of Gérard de Ridefort's death, he was not even a member of the Templar Order. However, the senior knights had become increasingly opposed to Masters fighting on the front line, and the capture and beheading of Grand Master Gerard de Ridefort became the final straw. They delayed elections for over a year so that the rules regarding active service of Grand Masters could be reviewed. During this hiatus, de Sable did join the order, just in time to be considered for election. When he was made Grand Master, he had been a Templar knight for less than a year.