Complex sentence: In January 1815, Decatur's squadron was assigned a mission in the East Indies, however, the British had established a strict blockade in the squadron's port of New York, therefore restricting any cruises.
Split into simpler sentences: In January 1815, Decatur's squadron was assigned a mission in the East Indies. However, the British had established a strict blockade in the squadron's port of New York, therefore restricting any cruises.