Battle of the Alamo 18-pounder Replica and Construction of the Southwest Corner Ramp Underway

February 23, 1836 — The Mexican Army arrives in Bexar and gives the Alamo Defenders the opportunity to surrender or be put to the sword. In response, William Barret Travis orders the 18-pounder, located at the southwest corner of the fort, to be fired into the Mexican encampment.

Moving forward to 1917, the cannon, which had been mounted on a plinth in San Pedro Springs Park disappears, leaving us with many questions today. Where did it go? How large was it? What did it look like?

In the Fall of 2020, the Alamo released “The Alamo 18-Pounder Cannon: Research to Replica.”

This report told the story of the 18-pounder cannon and its mysterious disappearance, and detailed the research done to determine the age, size, and style of cannon in order to create a 3D rendering. Much of the research done on the specs of the 18-pounder was based on cannons from the battle currently in the Alamo collection, as well as period photos of this and other cannons. Based on this information, the Alamo Research team, along with the help of artillery experts from around the world, determined that the Alamo 18-pounder was very likely a Swedish Finbanker cannon made in the late 1600s. With this guidance, along with the historic photos of the cannon and measurements taken from the cannon’s plinth, which is still located in San Pedro Springs Park, SRO Associates, Inc. was able to create a 3D rendering of what the cannon looked like when it was still intact.

18-pounder 3D model shown as transparent blue overlaid on top of the Fernando Raven photo.
SRO Architects. 18-pounder 3D model shown as transparent blue overlaid on top of the Fernando Raven photo.

With this exciting information, we are able to create a replica of the 18-pounder. Thanks to the rendering created by SRO, we know that the 18-pounder was approximately 7 feet in length, 1 foot, 3 inches in diameter at its widest area, and between 2,000–3,000 pounds. This length and weight is less than the average 18-pounder, which leads researchers to believe that the cannon started its life as a much smaller caliber cannon, likely a 9-pounder and then was bored out to be an 18-pounder.

Molten metal being poured into a mold
Photo courtesy of The Verdin Company.

Due to the large size of the cannon we needed to find a foundry that was able to handle creating such a large project. The Alamo found what it was looking for in The Verdin Company, which specializes in casting large bells and building oversized clocks. The foundry was established in 1842 in Cincinnati, Ohio and is located not too far from where the foundry that created the Twin Sisters was located. After Verdin has completed the creation of the 18-pounder tube, it will be sent to be mounted on a carriage.

Due to the incredibly heavy weight of the 18-pounder tube, The Alamo needed to find a company that was able to construct a carriage with the ability to hold all of that weight. Hansen Wheel and Wagon Shop of Letchner, South Dakota was selected for their expertise in constructing large, historically accurate wagons, carriages, and other horse drawn vehicles.

The replica of the 18-pounder is the first half of a two-part project — the other half is where the cannon will be located when it is complete and arrives on site.

Construction of carriage to hold 18 pounder cannon
Photo courtesy of Hansen Wheel and Wagon.

If you have visited the Alamo within the last week, you will have noticed fencing located at the southwest corner, the historic location of the 18-pounder. That’s because we are reconstructing the cannon ramp. After consulting primary sources and with experts in Alamo artillery, the cannon ramp was designed, is under construction, and like 185 years ago, will be the location of the 18-pounder.

In order to give visitors context for the cannon and ramp, the area will also have interpretive panels which detail the location’s origin during the mission period as the Charlí and later Losoya house, and how that building came to hold the cannon ramp and largest cannon in the fort.

Reconstruction of cannon ramp in historic location of 18 pounder cannon
Cannon ramp construction progress, February 10

After this year’s Commemoration of the 185th Anniversary of the Battle of the Alamo, a team from the Alamo will travel up to South Dakota and retrieve the cannon and upon their return, the 18-pounder will be rolled up the ramp and once again take its place at the southwest corner of the fort.

The estimated time for the cannon’s arrival and installation on the ramp is late March, so keep an eye out for updates as well as a date for the unveiling.