Battle of San Pietro The Battle of San Pietro , also known as the Battle of Crocetta or the Battle of Parma was a battle fought on June 29 , 1734 , between troops of France and Sardinia on one side , and Habsburg Austrian troops on the other , as part of the War of Polish Succession , between the village of La Crocetta and the city of Parma , then in the Duchy of Parma . Austrian troops assaulted an entrenched Franco - Sardinian position , and were ultimately repulsed , due in part to the death of their commander , Florimund Mercy , and the wounding of his second in command , Frederick of Württemberg . Both sides suffered significant casualties in the battle , which lasted for most of the day . Background . Following the death in February 1733 of King Augustus II of Poland , European powers exerted diplomatic and military influence in the selection of his successor . Competing elections in August and October 1733 elected Stanisław Leszczyński and Frederick August , Elector of Saxony to be the next king . Stanisław was supported primarily by France , while Frederick August was supported by Russia and the Habsburg Emperor Charles VI . On October 10 , France declared war on Austria and Saxony to draw military strength away from Poland , and shortly thereafter invaded both the Rhineland and the Habsburg territories in what is now northern Italy . The Italian campaign was conducted in conjunction with King Charles Emmanuel III of Sardinia , to whom France had promised the Duchy of Milan in the Treaty of Turin , signed in September 1733 . Allies take Milan . Starting in October 1733 , a combined Franco - Sardinian army , numbering over 40 , 000 and led by Charles Emmanuel , rapidly took control of Milanese territory without significant opposition from the roughly 12 , 000 Austrian troops defending the duchy . After the conquest of Tortona in February 1734 , the fighting season slowed and the army camped for the winter . The army was joined in November 1733 by the 81 - year - old French Marshal de Villars . He and Charles Emmanuel disagreed on strategy , as the latter , distrustful of the French , wanted to secure Milan for himself , while Villars wanted to secure the southern ends of the passes through the Alps to prevent Austrian reinforcements from reaching Italy . Charles Emmanuel ' s tactics including deliberately delaying military movements that were unfavorable to his aims . Frustrated by these tactics , Villars asked to be recalled in May 1734 . En route to France , he fell ill , and died in Turin in June . The French troops in the army were then placed under the command of generals de Broglie and Coigny , who were made Marshal . Late in June 1734 , Charles Emmanuel returned to Turin , because his wife Polyxena of Hesse - Rotenburg was sick . He asked the French marshals to avoid engaging in offensive actions until he returned , although this was likely another delaying tactic on his part . Austrian campaign . In response to the allied seizure of Milan , Austria organized a relief army . Due to Charles Emmanuel ' s insistence on completely securing Milanese territory , some Austrian troops were able to cross the Alps to the stronghold of Mantua as early as November 1733 , bringing the troop strength there to about 7 , 000 . By the end of the year the garrison had swollen to 12 , 000 , mostly due to troops pulling out of Milanese strongholds . Frederick of Württemberg established patrols along the Po and Oglio Rivers to monitor allied movements in January 1734 , and fortified the Tyrolean border with Milan . By March the army ' s size had risen to 24 , 000 , and Field Marshal Florimund Mercy had taken command of the forces . He continued to maintain a defensive posture , as he thought that offensive action would leave either Mantua or the Tyrolean border too weakly defended . It was not until early April that the Austrian army began marching out to face the allies , massing along the Mincio River . Prince Eugene of Savoy , in a letter dated April 26 , ordered Mercy to begin the campaign ; total Austrian forces in northern Italy had grown to more than 55 , 000 . On May 1 the left wing of the Austrian army began crossing the Po River , forcing the French detachments on the southern bank to retreat toward Parma . Throughout May , that wing , commanded by Frederick of Württemberg , moved upriver toward Parma , while the right wing , under Marshal Mercy , moved more slowly , delayed by the need for provisions and a stroke suffered by the aging Mercy , that deprived him of his sight . On June 1 , Frederick dislodged a detachment of French troops that were stationed to protect a bridgehead at Colorno , not far from Parma . From June 3 to 8 , the bulk of the allied army crossed the Po at Sacca to join the defensive position there . On June 4 and 5 a detachment of Sardinian troops drove the Austrians from Colorno , who retreated to Sorbolo to plan an attack against the allied position at Parma . Battle . Marshal Coigny determined to make a stand at Parma , and on June 28 established a strong position outside the city walls . Anchoring his left flank to the city ' s defenses , he placed the right at the village of Crocetta , where it was further protected by swampy areas of the Taro River . The road between Crocetta and Parma ran on a causeway , and Coigny had deep trenches dug on either side of the road . Marshal Mercy crossed the Taro canal at the head of his army and at about 10 am fired on the French advance posts , who withdrew . On reaching Crocetta , Mercy ordered Frederick , who had command of the Austrian left , to attack without delay . The Prince objected that he first had to cross more troops over the river and align them . Then Mercy said " Je vous laisse faire et je ferai la chose à ma mode ( Do what you want , I will do it my way ) " and led the right into battle . His troops began advancing , filling in the trenches with fascine s amid a withering bombardment by the allies . The first wave was repulsed , but Mercy persisted in the attack , ordering fresh regiments into the assault . They continued to work filling the trenches , using the piled bodies of their comrades in the effort . They were about to take the first French line when Mercy was struck and killed by a musket ball , creating confusion and disorder within the lines . Frederick then arrived to take command and restore order . The Austrians gained control of the causeway and began filling the trench on the other side , this time using the accumulated bodies of their enemies . Frederick had two horses shot out under him , and eventually withdrew from the battle with a minor wound . Hotwever , the Austrians persisted in the attack , driving the French to the walls of Parma amid continued heavy fighting . There the French made a desperate stand , and successfully stopped the Austrian advance . The Austrians then withdrew to the south after the onset of darkness . Aftermath . The Austrians lost 6 , 172 killed and wounded , including Marshal Mercy and 6 generals . There were also a great many deserters . The French lost 4 , 000 killed and wounded and the Sardinians 400 . While the allies held the battlefield , it was not considered a great victory due to the heavy casualties . Frederick found refuge in the Montechiarugolo castle , where he wrote a report of the battle to the emperor , blaming the failure on Mercy ' s recklessness . The Austrian eventually retreated to the Secchia River , where they were joined in July by reinforcements and a new leader , Field Marshal Königsegg . There was little significant conflict as the two armies faced each other across the Secchia until September , when Königsegg began a series of moves that culminated in the Austrian defeat at Guastalla , again with heavy casualties , on September 19 , after which the Austrians retreated to the Oglio River , a position they maintained for the rest of the year . The battle was witnessed by the population of Parma and in particular by Venetian playwright Carlo Goldoni , who happened to be in the city .