 Complete the following phrase:  In 1812 Lavalle joined the Regiment of mounted grenadiers as a cadet. By 1813 he reached the grade of lieutet and moved to the army, which under orders of Carlos María de Alvear besieged Montevideo. Lavalle fought against José Gervasio Artigas in 1815 and in the Battle of Guayabos under the command of Manuel Dorrego. In 1816 Lavalle moved to Mendoza to join the Army of the Andes of the liberator José de San Martín and fought in 