The Piave River 1809 order of battle shows the units and organization for the Franco-Italian and Austrian Empire armies that fought in the Battle of Piave River on 8 May 1809. Eugène de Beauharnais, the viceroy of the Kingdom of Italy defeated Archduke John of Austria. Eugène's Advance Guard crossed the river first and was assailed by Austrian cavalry and artillery. The French cavalry routed the opposing cavalry and captured 14 enemy guns. A lull followed as John arranged his infantry in a formidable defensive position. Meanwhile, Eugène struggled to pour reinforcements into the bridgehead as the Piave rose dangerously. In the afternoon, the viceroy sent Paul Grenier to drive back the Austrian left while Jacques MacDonald mounted an assault on the center. The attack succeeded in breaking the Austrian line and compelling John to order a retreat.