 Constantine remained aloof from the Italian conflict , however . Over the spring and summer of 307 AD , he had left Gaul for Britain to avoid any involvement in the Italian turmoil ; now , instead of giving Maxentius military aid , he sent his troops against Germanic tribes along the Rhine . In 308 AD , he raided the territory of the Bructeri , and made a bridge across the Rhine at Colonia <unk> ( Cologne ) . In 310 AD , he marched to the northern Rhine and fought the Franks . When not campaigning , he toured his lands advertising his benevolence , and supporting the economy and the arts . His refusal to participate in the war increased his popularity among his people , and strengthened his power base in the West . Maximian returned to Rome in the winter of 307 – 308 AD , but soon fell out with his son . In early 308 AD , after a failed attempt to usurp Maxentius ' title , Maximian returned to Constantine 's court . 
