u/LefebvreDesnouettes

Pursuing Johann’s retreating army, Eugene caught up to him at the Piave river. Neither side was aware of the other, so the battle began accidentally as Eugene attempted to cross the river in force. Despite the potential for a disastrous defeat, quick thinking and good leadership allowed his force to hold out until most of his army crossed the river, after which he was able to drive Johann’s army back. After a poor initial performance in the early campaign, the Piave marks the first time Eugene develops as a great general, and is the beginning of his brilliant campaign into Styria and Hungary.

As the French were pursuing Hiller's army, one of Massena's divisions, on its own initiative, decided to pursue the fleeing Austrians across the Inn at the bridge at Ebelsberg, where Hiller's main force was located. Despite being significantly outnumbered and storming a fortified position, the French would seize the bridge and, after Massena sent in another division, Ebelsberg as well, due to French tenacity and Hiller's unwillingness to commit and fight. The combat would be among the most bloody and brutal of the entire Napoleonic Wars, characterized by desperate street fighting. Casualties were high on both sides, with the French losing 3,500 (a third of the initial division's total combat strength), the Austrians 8,200. 

Taken from John Gill's "1809: Thunder on the Danube, Vol.II":

>Flames also consumed Ebelsberg. What Pelet had called ”this cruel fire“ spread through the town and the castle, destroying sixty-seven of the eighty houses that made up the market area. Wounded men who had crept into buildings to escape the fighting were burned to death in the most horrible fashion. ”Ebelsberg offered a frightful spectacle; the streets were full of cadavers mostly consumed by fire, and burned wounded who had endeavored to leave the houses.” Markgraf Wilhelm remembered that the charred corpse in the windows ”seemed to beg for pity from the passers-by.“ Dr Meier of the Baden contingent entered the wreck of the town late that afternoon: ”Never did I see, not even in great battles such as Wagram, corpses and wounded lying so thickly next to and atop one another.“

>The effect on the combatants was profound. Major Charles Fare of the IV/69th Ligne described the battle as ”one of the most terrible that one could imagine.” ”I was covered with the blood of my brave men who fell near me,“ wrote GB Ledru. The hideous aftermath also left an indelible impression on everyone who passed through the town in the following days. The smouldering desolation and the hundreds of charred human bodies trampled by skittish horses and crushed under wheels of hastening guns and caissons left ”a feeling of intense horror and disgust, of which I have never been able to shake off the memory,” recalled Lejeune. Weeks later, Ebelsberg was still nothing but a blackened spot on the landscape, ”a mass of smoking ruins and cadavers.”

>Many officers and men, captured by curiosity, visited this morbid site on the following day: ”Tears rolled from all eyes and no one dared to proffer a single word.” ”I have never seen anything more frightening than those burned cadavers that no longer bore any resemblance to the human,“ recalled bandsman Girault of the 93rd Ligne, ”I have walked many fields of battle, but I have never been stricken by such emotion.” Napoleon, visibly disturbed, told his staff as he viewed the carnage on 4 May: ”Every war agitator should see a parallel monstrosity; they should know what their projects cost in evil to humanity.”