Kaunitz was an amateur botanist, and had in his luggage several collections of bulbs from floral plants unknown in Argentina. On 20 March 1812 he joined the Army of the North, with the rank of lieutenant colonel, commanding the artillery of Belgrano's army. He made excellent relations with the general, being of assistance at the battles of Las Piedras (1812) and Tucumán, but he had uneasy relations and some enmities with other army officers which made him leave this army after the last battle. He continued the campaign at the front in Montevideo, where in 1813 he would found the first sapper corps in the army. At the beginning of 1814 the government commanded him to fight and capture José Gervasio Artigas, but he fell wounded at the battle of Espinillo fighting Fernando Torgués, whom pardoned his life and released him along with his adjutant, lieutenant Hilarión de la Quintana.