Short answers, pulled from the story.
Louis Charles Antoine Desaix de Veygoux entered the world on the 17th of August 1768 inside the Château d'Ayat. His father Gilbert des Aix held the title Lord of Veygoux and owned a manor in Charbonnières-les-Varennes.
Desaix joined the staff of Charles Louis Victor de Broglie and escaped the guillotine through sheer luck and service despite his dangerous association with Jacobins. Conspicuous actions soon brought him into favor with the Republican government allowing him to attain division command by 1794.
British Admiral Lord Keith declared Desaix to be a prisoner of war after he arrived in Livorno and refused to recognize his status as a general officer. Superior orders from the British Admiralty eventually released him from custody following this detention.
A musket ball killed Desaix instantly at Rivalta on the 14th of June 1800 while he led three regiments against the enemy center. He marched toward cannon fire heard three days after arriving in Italy and died at the moment of victory.
A monumental tomb with sculptures by Jean-Guillaume Moitte serves as his final resting place at the Great St Bernard Hospice. His body originally lay in Milan before being moved to the Hospice in 1805.