Complex sentence: In January of 1882 he was posted to 4th company under the command of Ignacio Carrera Pinto, the unit that was in charge of the garrison of the town of Concepción.
Split into simpler sentences: In January of 1882 he was posted to 4th company under the command of Ignacio Carrera Pinto. The unit was in charge of the garrison of the town of Concepción.