Plautius' political career started in a unknown way, probably as a military tribune. In approximately 36 he was appointed governor of the Roman province of Pannonia, in the region of modern Hungary, where he acquired experience as general. Emperor Claudius considered him a trustful man and gave him the command of the Roman invasion of Britain in May 43. The army was composed by four legions: II Augusta, IX Hispana, XIV Gemina and XX Valeria Victrix, approximately 20,000 auxiliary troops. The result was a Roman victory that was consolidated in the following years turning Britain into a Roman province. After the conquest, Aulus Plautius was named the Roman governor of Britain, until 46. On his return to Rome and civil life, Plautius was granted with ornamenta triumphalia, a very highly regarded award in ancient Rome.
Plautius' occupation army had, therefore, captured almost all of the arable land in the province during the first three years in Britain, and these conquests were seemingly delineated by a Roman road which ran from Exeter in Devon through Leicester in the midlands all the way to Lincoln.
Plautius celebrated his Ovation upon returning to Rome in early 47, and this was to be the last time the distinction was granted to anyone outside of the immediate imperial family.
AulusPlautius was consule suffectus in the latter half of 1 BC, with Aulus Caecina Severus his colleague.
By the 40s AD the Catuvellauni had displaced the Trinovantes as the most powerful kingdom in south-eastern Britain, taking over the former Trinovantian capital of Camulodunum (Colchester), and were pressing their neighbours the Atrebates, ruled by the descendants of Julius Caesar's former ally Commius.
AulusPlautius, a distinguished senator, was given charge of four legions, totalling about 20,000 men, plus about the same number of auxiliaries.
Cassius Dio presents this as Plautius needing the emperor's assistance to defeat the resurgent British, who were determined to avenge Togodumnus.