This is the saddle that General Santa Anna rode during the Texian revolution. It was captured at the battle of San Jacinto and acquired by Sam Houston.  Houston presented it as a gift, writing:

TO ROBERT HOUSTON McERDEN [McEWEN],

Nacogdoches, Texas 7th Sept. 1836.

Cousin Robert:  Through the care of Major R. Lloyd, a gentleman of Columbus, Mississippi, I take pleasure in forwarding to you as a present, the saddle and Bridle rode and owned by Gen'l Santa Anna, at the battle of San Jacinto.  It was presented to him by Gen'l Seisma, and is said to have cost $850.00....

He gave for the caparisons $325.00. I had no ostentatious foible to graify, or idle vanity, by becoming the owner of the spoils taken in Battle, because they once belonged to any particular individual.  I present them to you as an evidence of grateful affection, and should you not desire to retain them, you have my permission to present them to General Jackoson, or to Doctor John Shelby; otherwise they are to remain in your family as my collateral kindred.

You will please present my affectionate regards to my dear Cousin H. & family.

Sam Houston"

The saddle can now be seen in Huntsville at the fantastic @SHMMuseum in Huntsville, which is a super interesting museum to visit.