Short answers, pulled from the story.
Lieutenant General Peter Quasdanovich commanded the Austrian Right Column. This corps numbered 18,000 men and consisted of four mixed brigades led by General-Majors Peter Karl Ott, Heinrich XV Prince of Reuss-Plauen, Joseph Ocskay, and Johann Rudolf von Sporck.
Napoleon Bonaparte bluffed the Austrian army on the 4th of August during the Battle of Lonato. He faced only 1,200 French soldiers against 3,000 Austrians and ordered his aide-de-camp Berthier to issue bogus orders for grenadier and artillery units to force Oberst Knorr to surrender 2,000 men and 3 cannons.
The Austrians lost 23 cannons and suffered at least 5,000 killed, wounded and captured during the battles on the 3rd and the 4th of August. French losses reached at least 2,000 men in these engagements which preceded the Battle of Castiglione on the 5th of August.
Only General of Division Pierre Francois Sauret's 4,500-man division defended the mountains west of Lake Garda when Field Marshal Dagobert von Wurmser set out from Trento on the 29th of July. Garrisons held Salò on the western shore, Gavardo on the Chiese River, and Desenzano del Garda at the southwestern corner while Brescia was held by just three companies of infantry.
Joseph Ocskay surrendered his brigade because he was hemmed in by enemies after his outnumbered men were driven from Lonato and pursued toward Desenzano. His forces scattered across the countryside following a counterattack by Masséna and assaults from the brigades of Pijon, Claude Victor, Antoine Rampon, and Jean Lorcet.