 Stephen returned to the Duchy in 1137, where he met with Louis VI and Theobald to agree to an informal alliance against Geoffrey and Matilda, to counter the growing Angevin power in the region.Stephen formed an army to retake Matilda's Argentan castles, but frictions between his Flemish mercenary forces and the local Norman barons resulted in a battle between the two-halves of his army.The Norman forces then deserted the King, forcing Stephen to give up his campaign.