Complex sentence: Beni continued to steal horses from the Pike's Peak Express Company and Slade vowed to hunt him down, but Beni decided to ambush Slade at Slade's own ranch at Cold Springs.
Split into simpler sentences: Beni continued to steal horses from the Pike's Peak Express Company, and Slade vowed to hunt him down. Beni attempted to ambush Slade at Slade's own ranch at Cold Springs.