Under Claudius, the empire expanded for the first time since the reign of Augustus. The provinces of Thrace, Judea and three other provinces were annexed during his term. The annexation of Mauretania, begun under Caligula, was completed after the defeat of rebel forces, and divided into two provinces. The most important new expansion was the conquest of Great Britain (). In 43 , Claudius sent four legions to Britain. The island was an attractive target for Rome because of its wealth – particularly mines and slaves. It was also a haven for Gallic rebels and the like, and so could not be left alone much longer. Claudius himself traveled to the island after the completion of initial offensives, bringing with him reinforcements and elephants.