Complex sentence: The trio had held control over Lincoln County since the early 1870s and, as well, had the beef contract for nearby Fort Stanton in addition to running a well-known and patronized dry-goods store in the town of Lincoln.
Split into simpler sentences: The trio had held control over Lincoln County since the early 1870s. The men had the beef contract with nearby Fort Stanton and ran a well-known and patronized dry-goods store in the town of Lincoln.