Complex sentence: By the 21st century Hardwick had expanded its base of specialty store retailers with catalog and department store accounts, and taking advantage of domestic production increased contract manufacturing with entities as diverse as the U.S. Military and Major League Baseball umpires.
Split into simpler sentences: By the 21st century Hardwick had expanded its base of specialty-store retailers with catalog and department store accounts. Its domestic production enabled the company to increase contract manufacturing with entities as diverse as the U.S. military and Major League Baseball umpires.