Answer:
the Union.
Step-by-step explanation:
As we know, the Northern United States (union) was characterized by its manufacturing development, with the existence of small agricultural properties, in which there was a predominance of free wage labor. The South, on the other hand, was characterized by the plantation system, that is, the large property with the monoculture based on African slave labor.
The union had a much greater industrial strength than the Confederates and this reflected a lot in the secession war. In addition, the union had federal forts in the southern states, in addition to those established in the northern states. This allowed the union to have a strong defense and to advance in the conquest of the territory.