IIRC the day before, February 22nd, Santa Anna himself was 20 miles west of San Antonio on the Medina River. He got word around noontime that day that the Texian rebels were planning a celebration that very evening.

That afternoon he dispatched a large force of lancers (cavalry) to go crash that party. The commander of that force was a cautious man and, rather than enter the town as darkness was falling, made camp on Leon Creek maybe five miles west of town. If he had followed orders and crashed that party the Alamo standoff woulda been nipped in the bud.

"...if the gentlemen of Virginia shall send us a dozen of their sons, we would take great care in their education, instruct them in all we know, and make men of them." Canasatego 1744