As the Roman occupation of Britain was coming to an end, Constantine III withdrew the remains of the army in reaction to the Germanic invasion of Gaul with the Crossing of the Rhine in December 406. The Romano-British leaders were faced with an increasing security problem from seaborne raids, particularly by Picts on the east coast of England. The expedient adopted by the Romano-British leaders was to enlist the help of Anglo-Saxon mercenaries (known as ), to whom they ceded territory. In about 442 the Anglo-Saxons mutinied, apparently because they had not been paid. The Romano-British responded by appealing to the Roman commander of the Western empire, Aëtius, for help (a document known as the "Groans of the Britons"), even though Honorius, the Western Roman Emperor, had written to the British in or about 410 telling them to look to their own defence. There then followed several years of fighting between the British and the Anglo-Saxons. The fighting continued until around 500, when, at the Battle of Mount Badon, the Britons inflicted a severe defeat on the Anglo-Saxons.