According to plan, Kléber made the first move, advancing south from Düsseldorf against Württemberg's wing of the Army of the Lower Rhine. On 1 June 1796, a division of Kléber's troops led by François Joseph Lefebvre seized a bridge over the Sieg from Michael von Kienmayer's Austrians at Siegburg. Meanwhile, a second French division under Claude-Sylvestre Colaud menaced the Austrian left flank. Württemberg retreated south to Uckerath but then fell further back to a well-fortified position at Altenkirchen. On 4 June, Kléber defeated Württemberg in the Battle of Altenkirchen, capturing 1,500 Austrian soldiers, 12 artillery pieces and four colors. Charles withdrew the Austrian forces from the Rhine's west bank and gave the Army of the Upper Rhine the principal responsibility to defend Mainz. Three future Marshals of France played significant roles in the engagement: François Joseph Lefebvre as a division commander, Jean-de-Dieu Soult as a brigadier and Michel Ney as leader of a flanking column.