While organizing my old photos I came across 2007 pictures from a visit to Castillo de San Marcos, a fort in St. Augustine, Florida. The fortress was built by the Spanish as part of the time they occupied Florida.
The fortress is of the typical “bastion” type. I am not an expert in this era so I relied on wikipedia which had a nice description. Apparently the grades were built so that cannon would be more effective aiming downward as attackers neared the fortress.
Here is a view of one of the cannon pointed out towards the ocean from which attackers may arrive.
This is a view of the fort itself with the courtyard in the middle.
There were many cannons at the fort. The cannons weren’t all from that fort; some were donated from Spain or other museums. This is a four-pounder.
Here is a 16 inch mortar.
Note the fine detailing on these cannon. Very interesting.
Some of the cannons bear the words “ultima ratio’ which refers to God (Who has the highest order of thought) but may also be translated as the Final Argument in a dispute.
The fortresses are designed to resist cannon fire by having walls that deflect cannon balls rather than try to stop them – a theory of Vauban’s first implemented in the forts of the Spanish Netherlands.
Reminds me of some of the Spanish forts on the entrance to Cartejena’s harbor – that was where all the gold from South America left for Spain.
The fort looks like El Morro in San Juan Puerto Rico.
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Arghh! Didn’t come out.
This is I think one of the earliest Spanish forts in North America.
You could see how much smaller people were in those days from the height of the observation windows (about 5′).
There is another smaller fort that was an outpost guarding the inlet to the intercoastal waterway about 20 miles south of St. Augustine that is also fascinating to visit.
“The fortresses are designed to resist cannon fire”: so it wasn’t Injuns it was designed against. Pirates, French, English?
The stone from which this fort was constructed was very soft and simply absorbed cannon shot instead of deflecting it. This prevented violent concoidal fractures on the interior face of the the walls when struck by shot. Hard stone transmits the shock wave of the impact of shot clear through the wall and can cause the interior face of the wall to spall off with deadly force.
It’s an interesting site and worth visiting if you are nearby. It has the distinction of having been used by three or four different countries at different times. Old St. Augustine was one of the only walled cities in North America (I think Montreal was the other one).
Mr. Adair’s comment merits mention of the High Explosive Squash Head (HESH), which was used primarily against tanks in WW2, although it was originally developed for use against concrete.
Basically the same principle is involved; upon impact the shock wave passes through the target (usually a tank), breaking off metal pieces on the interior side, which then ricochet around the inside of the tank, with resulting mayhem. A British invention, it was one of an array of warheads for guns and missles. HESH use continued into the 1970s.
There are many tank museums with samples of what the M1A1 shoots at other tanks – basically a depleted uranium or titanium dart about 18 inches long or so shot at incredible speeds, meant not to explode but use the kinetic energy to pierce the opposing tank and cause untold insanity inside it, as Cris explains above.
The British still use HESH rounds, including with their Challenger 2s. It’s the main reason why they still use rifled tank guns rather than the smoothbores favoured by the USA/Germany.
You can’t fire SABOT/APFSDS rounds from a rifled barrel hence the continued use of HESH. However I think they misunderstand the point of smoothbore guns and SABOT rounds. Because the finned dart has a much lower frontal area than a traditional 120mm round and is lighter, it travels at a much higher speed. That means a flatter trajectory and a shorter flight time, both of which contribute to improved accuracy. Yes, rifled rounds are spin-stabilised but the target vehicle has a lot more time to make a maneuver so that it is no longer in the path of the projectile before it strikes.
Given the choice, I’d rather use APFSDS than HESH for that reason, even if HESH are effective at causing damage when they do hit (and are not completely useless against most soft targets like APFSDS are).
Note that the DU darts are also pyrophoric and as a result can ignite fuel or ammunition in the target, with explosive results. That’s one reason to prefer DU over tungsten (the other being that there’s a lot of DU left over after enriching uranium, eg, when making nuclear warheads).
A great place to hang out for the afternoon. I especially enjoyed the cannon drill and firing. (great sound out over the river) Felt bad for the reenactor guys in those wool period uniforms,though. They were visibly uncomfortable.
>>> Because the finned dart has a much lower frontal area than a traditional 120mm round and is lighter, it travels at a much higher speed. That means a flatter trajectory and a shorter flight time, both of which contribute to improved accuracy.
This is of less value with modern fire-control systems, I’d think. I recall reading some commentary after the Gulf War, complaints by the Iraqi tank men that it just wasn’t fair having to fight against the M1 Abrams, because they’d have to stop, take aim, and shoot, while the Abrams would be barreling along at 60mph across the desert, and be able to shoot accurately at their targets.
It’s been 20 years since then, I’d suspect that the techniques used for anti-mortar counter-battery fire, where they radar trace the attacker’s shots back to their source and be counter-firing to take it out within a scant time frame would/could probably also be applied to tank fire. I would assume current tanks can see where shots are coming from and counterfire within seconds to take out that specific target.
Speculation, but I find it hard to believe I’m the first to think of this stuff and I’m guessing the equipment can probably easily be placed in the field.
IGotBupkis – it was even worse than that. The Abrams was already targeting the NEXT victim while it was shooting the first tank. The only thing holding the computer back is the actual loading of the projectile. While moving out. It really wasn’t fair.
One interesting finding from American research into fortifications in the early 1800s was that brick was better than granite, precisely because of the spallation effect within the fort.
Another factoid you might find interesting is that wooden forts on the frontier needed 4 inches of solid wood to stop a musket ball.
I’ve done some professional research into fortifications because of my work protecting nuclear power plants.
>>> IGotBupkis – it was even worse than that. The Abrams was already targeting the NEXT victim while it was shooting the first tank. The only thing holding the computer back is the actual loading of the projectile. While moving out. It really wasn’t fair.
Yet another reason I want citizens to own guns. As bad as it would be to take on the modern US military with sub-automatic weaponry, it’d be one hell of a lot less armed with only knives and pitchforks. And as long as citizens have guns, anyone who might think of mounting any kind of coup would be much, much more wary of the attempt.