Calcasieu Pass was an important spot in the river. The Trans-Mississippi Department depended on clear passage for providing supplies of corn, beef, muskets, gunpowder and reinforcements as well.
For almost three years the Calcasieu River was of little or no interest to either side of the war, even though the Pass itself was only about thirty-eight miles from the Texas-Louisiana border. Even so, after the war began, one company had erected a mud fort on the island which had miles of marshy land. This was an attempt by the Confederates to keep Union foraging parties from gaining access to food sources needed by the Confederate troops. The island was virtually abandoned during the winter of 1863-1864 and because of its terrain didn’t seem worthy of invasion or defense. (From The von Rosenberg Family of Texas: The Civil War Years, by Ann Barnes) http://tinyurl.com/nq2r7yg