Campaigns in 286 and 287 Maximian realized that he could not immediately suppress Carausius and campaigned instead against Rhenish tribes. These tribes were probably greater threats to Gallic peace anyway and included many supporters of Carausius. Although Maximian had many enemies along the river, they were more often in dispute with each other than in combat with the Empire. Few clear dates survive for Maximian's campaigns on the Rhine beyond a general range of 285 to 288. While receiving the consular
fasces on 1 January 287, Maximian was interrupted by news of a barbarian raid. Doffing his toga and donning his armor, he marched against the barbarians and, although they were not entirely dispersed, he celebrated a victory in Gaul later that year. Maximian believed the Burgundian and Alemanni tribes of the
Moselle-
Vosges region to be the greatest threat, so he targeted them first. He campaigned using
scorched earth tactics, laying waste to their land and reducing their numbers through famine and disease. After the Burgundians and Alemanni, Maximian moved against the weaker Heruli and Chaibones. He cornered and defeated them in a single battle. He fought in person, riding along the battle line until the Germanic forces broke. Roman forces pursued the fleeing tribal armies and routed them. With his enemies weakened from starvation, Maximian launched a great invasion across the Rhine. He moved deep into Germanic territory, bringing destruction to his enemies' homelands. By the end of 287, he had the advantage and the Rhenish lands were free of Germanic tribesmen. Maximian's panegyrist declared: "All that I see beyond the Rhine is Roman." , Maximian's
praetorian prefect and husband to his daughter Theodora
Joint campaign against the Alamanni Early the next year, as Maximian made preparations for dealing with Carausius, Diocletian returned from the East. The emperors met that year, but neither date nor place is known with certainty. They probably agreed on a joint campaign against the Alamanni and a naval expedition against Carausius. Later in the year, Maximian led a surprise invasion of the
Agri Decumates – a region between the upper Rhine and upper Danube deep within Alamanni territory – while Diocletian invaded Germany via
Raetia. Both emperors burned crops and food supplies as they went, destroying the Germans' means of sustenance. They added large swathes of territory to the Empire and allowed Maximian's build-up to proceed without further disturbance. In the aftermath of the war, towns along the Rhine were rebuilt, bridgeheads created on the eastern banks at such places as Mainz and Cologne, and a military frontier was established, comprising forts, roads, and fortified towns. A military highway through Tornacum (
Tournai,
Belgium), Bavacum (
Bavay, France), Atuatuca Tungrorum (
Tongeren, Belgium), Mosae Trajectum (
Maastricht, Netherlands), and Cologne connected points along the frontier.
Constantius, Gennobaudes, and resettlement In early 288, Maximian appointed his praetorian prefect
Constantius Chlorus, husband of Maximian's daughter Theodora, to lead a campaign against Carausius' Frankish allies. These Franks controlled the Rhine
estuaries, thwarting sea-attacks against Carausius. Constantius moved north through their territory, wreaking havoc, and reaching the
North Sea. The Franks sued for peace and in the subsequent settlement Maximian reinstated the deposed Frankish king
Gennobaudes. Gennobaudes became Maximian's vassal and, with lesser Frankish chiefs in turn swearing loyalty to Gennobaudes, Roman regional dominance was assured. Maximian allowed a settlement of
Frisii,
Salian Franks,
Chamavi and other tribes along a strip of Roman territory, either between the Rhine and
Waal rivers from Noviomagus (
Nijmegen, Netherlands) to
Traiectum, (Utrecht, Netherlands) or near Trier. These tribes were allowed to settle on the condition that they acknowledged Roman dominance. Their presence provided a ready pool of manpower and prevented the settlement of other Frankish tribes, giving Maximian a buffer along the northern Rhine and reducing his need to garrison the region. ==Later campaigns in Britain and Gaul==