Simplify the following text for a Grade 11 native English-speaking person.
Original: Also , in Britain in 184 , the governor Ulpius Marcellus re-advanced the Roman frontier northward to the Antonine Wall , but the legionaries revolted against his harsh discipline and acclaimed another legate , Priscus , as emperor .
Simplified: In Britain in 184 , the governor Ulpius Marcellus pushed the Roman frontier north to the Antonine Wall , but the soldiers revolted against his harsh discipline .