If that had been its purpose. More likely it was to deny the confederacy the use of even a small port.
The south would have also been deprived of blockade runners after Mobile fell in 1864.
At best the blockade runners going to Texas could barely keep Kirby Smith supplied. Virtually nothing that was landed there could have made it east, especially after Vickburg was cut in 1863. There were no railroads connecting Texas with any part of the Confederacy.
So in effect, a 40 man garrison at an earthen fort significantly altered the time and course of the war.
Pure conjecture on your part. Maybe it did and maybe it didn't, we'll never know for sure.
The invasion of Texas and seizing of the cotton was its purpose. It was the same purpose as the Red River campaign, which attempted to invade through the north.
At best the blockade runners going to Texas could barely keep Kirby Smith supplied.
It's better than nothing, and all indications from 1864-65 indicate that the runners in Galveston were among the most successful of the war. The estimation TAMU gives is a successful run almost once a week.
Pure conjecture on your part. Maybe it did and maybe it didn't, we'll never know for sure.
No conjecture. It is simple fact - The red river campaign would not have been needed had they succeeded earlier. You are correct that we cannot know for sure the specifics of what might have happened otherwise had Sabine Pass not stopped the invasion force, but that one contingency is known. Banks tried to invade from the north because his previous attempts to do the same from the gulf had failed. Had those previous attempts succeeded, he would not have tried from the north.