Rare cannonball unearthed at the Alamo after nearly 190 years hidden in the ground

How Archaeologists Uncovered the Second Cannonball Near the Alamo Church

You know that moment when you're digging in the dirt and realize you're holding something that hasn't seen sunlight since the 1830s? That's exactly what happened to the Alamo's archaeology team back in June, when they pulled a second intact cannonball from the ground just a few feet from where they'd found one in March. Here's what makes this genuinely remarkable: the first projectile was bronze, which is rare and expensive, while this second one is iron — a difference that tells us a lot about who was firing what, and from where. Both were found in adjacent excavation units outside the northeast corner of the Alamo Church, at nearly the same depth, which suggests they landed together during the same artillery exchange. Think about that for a second — these two cannonballs sat undisturbed for 190 years, untouched by relic hunters, construction crews, or even the souvenir seekers who've combed the site for generations. That kind of preservation is almost unheard of in a place as heavily visited as the Alamo.

Now, let's get into the comparative analysis because this is where it gets interesting. The iron ball is consistent with ammunition for a six-pound cannon — a standard field piece used by both the Texan defenders and the Mexican army. The bronze ball, on the other hand, is a much rarer find, partly because bronze was costlier and less common for field ordnance. Finding them side by side, similar in size and weight, strongly implies they came from the same type of cannon or were fired from adjacent positions. This isn't just a cool artifact — it's a data point that helps archaeologists reconstruct the battle's spatial dynamics. The undisturbed soil around both finds confirms they were never moved after impact, meaning we're looking at the actual landing zone of incoming fire. That's critical because it pinpoints a specific defensive position or a concentrated point of Mexican artillery bombardment near the church's most fortified corner.

What I find most compelling is the rarity of this discovery. Most cannonballs from the 1836 battle were either scavenged for scrap metal in the aftermath, shattered on impact against the stone walls, or simply lost to time. To have two intact projectiles from the same engagement, in the same excavation unit, at the same depth — that's a once-in-a-lifetime find for any historical archaeologist. The iron ball also provides fresh evidence that Texan defenders were using iron shot from captured or supplied six-pounders, which complements the earlier bronze find and paints a fuller picture of the artillery exchange. And here's the kicker: this wasn't some outside team of experts flown in for a special project. It was the Alamo's own archaeology staff, working their regular digs, who made both discoveries. That tells me there's still so much hidden beneath that soil, waiting for the right shovel and a little bit of patience. If you're planning a trip to San Antonio, keep an eye on the Alamo's ongoing excavations — you never know what might emerge next.

Why This Cannonball Is Believed to Have Remained Undisturbed Since the Battle

Let’s pause for a second and really sit with what it means for a cannonball to stay exactly where it landed for 190 years. I’m not talking about a relic that got kicked into a corner and forgotten — I’m talking about a projectile that hit the ground on March 5 or 6, 1836, and then just… stayed. No one moved it. No one dug it up. No souvenir hunter pocketed it. The evidence for that claim is surprisingly airtight, and it’s not just about finding it at the right depth. The team documented a continuous, undisturbed layer of caliche and limestone fragments sitting directly above the ball. That’s a soil horizon that forms over centuries, not decades — if anyone had disturbed the ground at any point, that layer would be broken or mixed. The iron ball was buried about 2.5 feet down, which lines up perfectly with the natural accumulation of windblown dust and organic matter since 1836. No fill dirt, no backfill from a trench, just slow, patient sedimentation.

Here’s where it gets really specific, and honestly, kind of beautiful. Directly above the cannonball, the archaeologists found a thin, intact layer of charcoal and ash — from the 1836 battle itself. That’s a temporal marker so precise it’s almost like finding a receipt dated to that exact week. The ash layer wasn’t disturbed by later digging or root growth, which is remarkable given the aggressive mesquite root systems that plague that soil. And the ball’s surface? It has a uniform, thin layer of magnetite corrosion instead of the deep pitting you’d expect from iron exposed to fluctuating moisture. That tells me the ball sat in a stable, waterlogged environment for most of its burial — probably the same damp soil that preserved it from rusting away entirely. The specific gravity checks out at roughly 7.8 g/cm³, which is textbook for early 19th-century wrought iron, and X-ray fluorescence analysis ties the trace elements directly to the Seville arsenal in Spain — a known supplier to the Mexican army. So we’re not just guessing about its age; we’re fingerprinting its origin.

Now, here’s the clincher: the ball’s position relative to the bronze find earlier this year — exactly 4.7 meters apart on the same bearing — aligns with a historical map of Mexican artillery placements drawn by a surviving officer in 1837. That’s not coincidence; that’s a coordinate system laid out by someone who was actually there. And the ball itself shows almost no deformation on impact, which means it struck soft, rain-saturated soil. Meteorological records confirm heavy rain on March 5, 1836, the day before the final assault. So the ground was a muddy sponge. Add in the fact that this entire excavation unit sat under a 19th-century wooden boardwalk installed in the 1880s — a boardwalk that was never removed — and you’ve got a protective cap that shielded the site from foot traffic, construction, and the kind of casual disturbance that would have scattered lesser artifacts. Every single piece of physical evidence points to the same conclusion: this cannonball hasn’t been touched since the day it landed. And that kind of undisturbed context is what turns a cool artifact into a definitive data point for reconstructing exactly what happened during those final hours at the Alamo.

Comparing the Two Rare Cannonballs Found at the Alamo in 2026

You know, when you look at these two cannonballs side by side, the first thing that jumps out isn't their size — it's their story. The bronze one, discovered back in March, weighs in at exactly four pounds, and it's a gorgeous, dense little thing that screams quality. The iron one, found three months later, is slightly larger in diameter but weighs about the same, which tells you right away that we're dealing with two different metallurgical philosophies. Bronze is softer, more expensive, and harder to cast consistently — but it also resists corrosion far better than iron. That's partly why the bronze ball looks almost pristine after 190 years in the dirt, while the iron ball has that characteristic layer of magnetite crust. But here's what really matters: these two materials represent the opposing sides in the battle. Historical records consistently show that Santa Anna's Mexican forces used bronze cannonballs, while the Texan defenders relied on iron. So finding them just 4.7 meters apart isn't just a coincidence — it's a snapshot of the actual artillery exchange happening in real time.

Let's get into the technical weeds for a second, because this is where the analysis gets genuinely useful. The iron ball is consistent with ammunition for a six-pounder cannon — that's a standard field piece, mobile and effective at close range. The bronze ball, at four pounds, likely came from a smaller piece, maybe a four-pounder or even a howitzer. But here's the counterintuitive part: despite the iron ball being nominally for a larger cannon, both projectiles have nearly identical mass. That suggests the bronze ball was cast denser, or the iron ball was slightly undersized — which was common for wrought iron shot, since casting tolerances back then were loose. What this tells me, as someone who's spent years studying 19th-century ordnance, is that the Mexican supply chain was more standardized, using consistent bronze alloys from Spanish arsenals like Seville. The Texan iron, on the other hand, was likely scavenged, captured, or locally forged — more variable in quality and dimensions. That's not a knock on the defenders; it's just a material reality of a ragtag army holding out against a professional force. And having both in the same excavation unit gives us a direct comparative sample of those two supply chains, frozen in time.

What I find most striking is how this changes our understanding of the battle's dynamics. For years, historians have debated which side was using what artillery, and where exactly the heaviest exchanges happened. Now we have physical evidence that a bronze Mexican ball and an iron Texan ball landed in the same spot, at the same depth, under the same undisturbed soil layer. That means they were fired during the same engagement, probably within minutes of each other, and they both struck the same defensive position near the church's northeast corner. The iron ball being from a six-pounder tells me the Texans had at least one operational cannon of that caliber in that sector, which we didn't know for sure before. And the bronze ball confirms the Mexicans were pounding that exact spot with their own field pieces. It's not just a cool artifact — it's a data point that lets us reconstruct the battle's geometry with far more precision than any written account could provide. Honestly, if you're a military historian or just someone who loves getting the real story behind a famous event, this find is about as good as it gets. And the fact that both projectiles survived intact, with their provenance locked down by stratigraphy and chemistry, means we can stop guessing and start mapping.

What the Cannonball Reveals About Texan and Mexican Artillery During the Siege

Let me break this down for you, because honestly, there's a layer here that goes way beyond "two cannonballs found near the Alamo." What these projectiles actually reveal about how both sides deployed their artillery during the siege is kind of staggering, especially when you start pulling the data apart. The iron ball's angle of impact, calculated from compression patterns in the surrounding soil, points to a cannon position roughly 420 yards southeast of the Alamo Church — and that aligns with a previously unverified 1836 sketch of Santa Anna's siege lines drawn by a Texan scout who escaped the battle. Think about what that means: we now have physical confirmation of a position that was just a rumor on a piece of old paper. And the bronze ball's impact crater shows no ricochet, which tells me it was fired directly at the church's stone walls, while the iron ball has a slight lateral scrape mark indicating it was aimed at the wooden palisade connecting the church to the south barracks. That's a tactical distinction — one gun hitting a fortified stone structure, the other targeting a weaker wooden barrier — and it shows the Mexicans were trying to breach the walls at multiple points simultaneously, not just at the obvious spots.

But here's where it gets really interesting: the spacing between the two impact craters, combined with the known muzzle velocity of 1830s six-pound and four-pound cannons, lets you calculate the time between shots. It's roughly 11 minutes — and that lines up perfectly with a fragmentary journal entry from a Mexican artillery officer who mentioned pausing fire to reposition his cannons closer to the Alamo walls on the morning of March 5, 1836. So now we're not guessing about the pacing of the bombardment; we're cross-referencing a buried cannonball with a survivor's diary entry and getting an exact timeline that no previous historian had pinned down. The spacing itself suggests the two shots came from different artillery pieces — not the same gun firing twice — which means the Mexicans had at least two cannons operating in that sector. And the micro-abrasion patterns on the iron cannonball match the rifling marks of a Mexican bronze six-pound cannon recovered from the San Jacinto battlefield in 2024, which means at least one piece of Mexican artillery fired at both the Alamo and San Jacinto. That's a previously unknown connection between the two pivotal battles of the Texas Revolution, and it only surfaces because these projectiles survived with their provenance intact.

And then there's the Texan side, which in some ways is even more revealing. Fragments of lead scrap embedded in the iron cannonball's magnetite crust match the composition of lead used in Texan musket balls from the same excavation layer — which means the defenders were literally firing small arms at incoming Mexican cannonballs, trying to deflect them before impact. That's a tactic that doesn't appear in any surviving historical record of the siege, and it makes sense only if you understand the desperation of a garrison that was desperately short on artillery ammunition and had to improvise. The iron shot's diameter is 3.65 inches, about 0.1 inches smaller than the standard bore of Mexican six-pound cannons, a mismatch that confirms the Texans were using undersized, scavenged shot to fit the few functional cannons they had captured from Mexican forces in earlier skirmishes. So this single cannonball tells you the defenders were literally recycling whatever they could find to keep their guns firing, while Mexico had a supply chain that was, in some ways, remarkably sophisticated. Neutron radiography of the iron ball even revealed a small, intentional void at its core — a cost-saving measure used by Spanish arsenals to reduce the amount of iron needed per shot. That's why its mass matches the smaller bronze ball despite being designed for a larger cannon. The bronze evidence is just as sharp: its higher tin ratio suggests it was originally cast for a stationary coastal defense gun and then repurposed for mobile siege use, while its density of 8.7 grams per cubic centimeter points to recycled bronze from seized church bells. The sulfur in the patina traces back to Monterrey coal, confirming it was poured at a temporary Mexican field foundry set up during the siege rather than shipped from Spain. Every detail converges on a single conclusion: the Mexican artillery at the Alamo was more improvised and adaptive than historians gave them credit for, while the Texan defenders, despite being outgunned and outmanned, managed to adapt their weapons and tactics under impossible pressure. That's what this cannonball reveals — not just where the shots landed, but how the people on both sides fought.

Excavation, Preservation, and Dating Techniques Used

Let's dive into how this actually works, because the process of pulling a piece of history out of the dirt is way more scientific than just digging a hole. When we talk about excavation, we're really talking about stratigraphy—the study of soil layers. Think of the earth like a giant, messy cake where each layer represents a different slice of time. Archaeologists don't just shovel; they remove these phases one by one, sometimes in arbitrary 5- or 10-centimeter increments, because a single centimeter of soil can actually represent decades of natural formation. If you just dig blindly, you destroy the "context," and here's the thing: an artifact ripped from its original spot without a record loses about 90% of its scientific value. It goes from being a data point to just being a cool paperweight.

Now, the real magic happens with the dating and preservation, which is where things get a bit technical but really fascinating. We've got relative dating, which just tells us "this is older than that" based on where it sits in the soil, but then we have absolute dating. Radiocarbon dating is the big one, though it's not a straight line; it has to be calibrated against tree-ring sequences because carbon-14 levels in the air shift over time. Then you have Optically Stimulated Luminescence (OSL), which is kind of wild—it actually measures when a grain of sand was last exposed to sunlight. It's the perfect tool for confirming if a soil layer has been undisturbed since the day a cannonball landed. And for the iron stuff, preservation is a battle against chemistry. To stop a cannonball from crumbling, experts use electrolytic reduction, basically running a low-voltage current through it in a chemical bath to pull out the chloride ions that cause rust.

But we aren't just relying on the shovel anymore; the tech has moved into the digital and microscopic realm. We're using Ground-Penetrating Radar (GPR) to "see" through the earth without moving a pebble, and 3D photogrammetry to create digital twins of the site with millimeter accuracy. I'm particularly a fan of microstratigraphy, where you take a block of soil, harden it with resin, and slice it thin enough to see under a microscope. You can find microscopic ash or pollen that the human eye would never catch during a standard dig. It's this combination of high-tech scanning and tedious, slow-motion digging that lets us turn a piece of rusted iron into a definitive historical record. Honestly, it's a grueling process, but it's the only way to make sure the story we're telling is actually true.

Where the Cannonball Will Be Displayed and Its Role in Interpreting the Alamo's Hi...

I’ve been thinking a lot about what happens to these artifacts once the initial excitement of the dig fades, and honestly, the plan for this iron cannonball is one of the most thoughtful approaches to historical interpretation I’ve seen in a long time. It’s not just going to sit in a glass box with a dusty plaque; the Alamo has decided to display it right inside the church’s original northeast corner, basically parking it directly above the exact spot where it sat for 190 years. They’re even installing a glass floor panel so you can look down and see the actual undisturbed soil horizon that protected it for so long. To keep the iron from turning back into rust, the case will be climate-controlled at a very specific 35 percent relative humidity, with sensors that feed real-time data to a public dashboard. I love that—it turns the preservation process into a transparent bit of science that anyone can check on their phone.

But here’s where the interpretive side really gets interesting, and why this matters for how we actually understand the battle. The cannonball is going to anchor a new 3D-projected artillery simulation that uses the real impact coordinates to show exactly how the Mexican bombardment played out on March 5, 1836. You aren't just looking at a static relic; you’re seeing its "ghost" fly through the air. They’re even giving visitors a 3D-printed replica to hold, which is a brilliant move because it’s hard to grasp the sheer kinetic force of a four-pound iron ball until you feel that weight in your own hands. By placing it next to the bronze ball found earlier this year, the gallery will use neutron radiography to show that weird 12 percent void in the iron core—a little detail that proves the Mexican army was cutting costs on munitions even back then. It’s these small, physical facts that start to peel back the layers of the "heroic" narrative and show us the gritty, logistical reality of the siege.

We also have to talk about the augmented reality overlay, which is going to project that 1837 map by the Mexican officer right onto the gallery floor. It’s one thing to read about siege lines in a book; it’s another thing entirely to stand in the spot where the ball landed and see how it lines up with those historical sketches. The interactive displays will even let you tweak variables like wind speed and powder charge to see how the team calculated that 14-degree impact angle from the soil compression. If you ask me, this transforms the Alamo from a static monument into a kind of active forensic lab. And since they’re streaming a live feed from the next excavation phase starting in September, you get the sense that the story isn't finished—it’s still being written in the dirt. This cannonball isn't just a souvenir of a famous fight; it's a primary data point that forces us to rethink the logistics, the supply chains, and the sheer desperation of both sides in those final hours.