The army considered sufficient for the contemplated war consisted of seven legions, viz., the first, the Minervia , the second, the Adjutrix , called also the Pia , and at a later period of the war, Trajana . After the war this legion was stationed in Lower Germany. The second legion at the end of the war received the decorations of a mural crown, and was raised to the equestrian rank.
Inscriptions show that the fourth, fifth, seventh, and eleventh, took part in each war.
The thirteenth legion seems to have had some share in the expedition, though not actually engaged in the campaign. It was left in reserve in Pannonia, through which country the emperor marched to the theatre of the war. The sixth and thirteenth legions both congratulated the fortunate commander on his personal safety. Inscriptions also indicate that other legions, such as the tenth and fifteenth, took some part, probably the charge of the fortified stations and river side ports of the Save and the Danube, which served as reserves and defences of the base of operations. Many of the corps employed were drawn for the army Trajan had already trained so well on the Rhine.