San Antonio Police Chief William McManus mingled in the crowd, which police estimated was 300 to 400 people. He chatted with rally organizers while a substantial police presence remained outside the event's perimeter.
The event was organized by several gun rights groups that advocate for the open carrying of long guns rifles and shotguns which is allowed under Texas law.
Open Carry Texas President C.J. Chivers told the crowd that he wanted to hold the event in San Antonio, because of a confrontation here between police and gun rights advocates a couple months ago.
"(The San Antonio Police Department) is no longer going to be messing with us," Chivers said from a podium, with the Alamo's famed Spanish mission behind him.
The city has an ordinance that limits the carrying of firearms, especially at public events.
Asked about the enforcement of that ordinance Saturday, McManus said, "there are too many issues associated with trying to enforce every ordinance here today." He said his priority was that people be able to exercise their constitutional rights and that everyone remain safe. He said police preparations had been underway for about two weeks.
Chivers and others credited police in helping to coordinate the event. Before the rally began, announcements were made to remove ammunition from rifle chambers and volunteers walked through the crowds inserting red straws in rifles to show the chambers were clear.
Colt Szczygiel, 27, a retired U.S. Marine rifleman who just moved to Converse, Texas from Connecticut in September, was excited to be making his first visit to the Alamo on such an occasion. With a Bushmaster ACR rifle hanging from his shoulder he read a plaque about the site's history like any first-time tourist.
"It's great to be able to come here with my rifle for the first time," he said. Texas' gun-friendly culture made the move all the more attractive coming from Waterbury, Conn., he said. He had participated in gun rights rallies there, but this was his first in Texas.
Reactions from tourists who just happened on the demonstration were varied.
Don Norwood, 49, of Little Rock, Ark., was visiting with his wife and daughter. He hadn't expected the demonstration, but gazing over the crowd, he said, "it's healthy, that's what America's about."
Asked if it made him nervous to approach the old mission chapel through the armed crowd, Norwood said, "no, they're not a threat to me."
A 21-year-old from Houston, who would only give his name as Neil, was a little more apprehensive. At the edge of the crowd he paused, while his girlfriend snapped photos.
"I was just trying to figure out what was going on and then I saw everybody carrying their weapons and I caught on," he said.
He described himself as impartial about the rally. "I don't own any guns, but I do feel people have the right to bear arms as per the constitution," he said.
He did express doubts though about the location. "Why here? Why come out in an open park? Why in front of a monument? I do think that's a little inappropriate."
It was a question raised earlier by the Alamo Defenders' Descendants Association. Lee Spencer White, its president, said her group considers the Alamo its family cemetery and as hallowed ground should remain free of demonstrations, which historically have been held on the adjacent plaza.
From 1905 to 2011, the Daughters of the Republic of Texas were the Alamo's custodians. But in 2011, lawmakers gave the state's General Land office control of the monument where Col. William Travis and 200 Texas defenders famously died in a siege with the Mexican army in 1836. It was Land Commissioner Jerry Patterson who approved the rally here.
"I respect the opinions of folks who say this is not the right place," Patterson said to the crowd on Saturday. "But I submit to you there's one standard we should apply to gatherings here at this sacred cradle of Texas liberty and that is whether our activity and our purpose would be supported by those men who gave it all."
Patterson, who is running for lieutenant governor, did ask attendees to not block the path to the mission and to leave their rifles and signs outside when entering the chapel. "Even though you can lawfully do that, we have a reverence for that location where those men died."