Made Like a Gun? Get a load of these cannons

Fort De Soto in Florida gives visitors a view of immense coastal defense mortars.

"There isn't much of the fort left," our hostess warned us on our visit to St. Pete Beach in Florida recently.

"I don't think there was much there to begin with," she added.

But as far as I was concerned, our visit to Fort De Soto Park at the entrance to Tampa Bay was full of historical treasure.

Her opinion might have been justified if you were expecting a moat and castle walls. But Fort De Soto, built around the time of the Spanish-American War, is invisible from most angles — as it was designed to be.

Big 12-inch mortars were hidden in pits but could
lob armor piecing shells onto the decks of  warships

In an era before the airplane, it made sense to hide coastal defense cannons in concrete pits largely surrounded by the dirt of an artificial mountain. The flat trajectory shells of enemy warships would have flown over harmlessly.

Meanwhile, the massive 12-inch mortar barrels inside the pits would lob shells almost straight upwards to crash down on the lightly armored decks of the approaching battleships.

That was the theory, anyway. The eight guns of Battery Laidley at Fort De Sota were never fired in anger (and only four of them remain at the fort today).

Mortars could fire shells weighting 800 to 1,046 pounds.

Their immense barrels remain impressive. Imagine a 12-inch shell this way: the diameter of a basketball is only 9.55 inches.

Hitting a moving target like a ship with a lobbed shell is obviously difficult, but these monsters would have had to hit a battleship the size of the Maine only once to be devastating.

Range was 6.8 miles, but a problem was that the mortars couldn't hit anything that was closer than 1.25 miles. Fast-firing 15-pounder guns were in position near the beach to deal with close, and fast moving targets.

Battleships did not remain the size of the Maine long, and Fort De Soto was obsolete before World War I began. The Army finally moved out in 1923, defeated by the hoards of mosquitoes.

Civil authorities eventually got those under control, giving Pinellas County a park with lovely beaches and one very well preserved fortress.

A ship enters Tampa Bay past vent covers for the buried magazines
of Fort De Soto. Inspired by the Spanish-American War of 1898,
the fort (named for a Spanish explorer!) didn't test fire its guns until 1903.

Coastal defense batteries fascinate me, as reminders of a time when the United States thought it was safe from attack behind its oceans.

But 12-inch mortars like those at Fort De Soto did fight for the United States and, incredibly, it happened in World War II, after they had long been antique technology.

Photo on display at Fort De Soto shows two 12-inch mortars
 firing, with their shells visible in the air.

It happened on the island of Corregidor, at the entrance to Manila Bay, and that battle has a special meaning for me. My friend Douglas Kalajian's father served at Battery Geary on Corregidor.

It's one of the stories Doug's Dad did tell him, and it is detailed in Doug's memoir, Stories My Father Never Finished Telling Me.

Mortars being fired with lanyards. The guns could also be fired
electrically from a buried "Firing Room" (surely a safer alternative).

Other historic coastal defense emplacements like Fort De Soto exist around North America, but most of their guns were scrapped long ago. Only Fort De Soto still has 12-inch mortars identical to those that fought and still remain in the ruins at Corregidor.

Two mortars remain in each of the two gun pits at Fort De Soto.
Originally there were four guns in each pit but with 12 men
loading and aiming each, congestion was a problem.

Observation posts sent target directions to the Relocating Plot Room,
which calculated gun settings and telephoned them to twin Data Booths.

Fortified Data Booths displayed aiming information
to the gunners by sliding out wooden slats.

Where's the fort? It's the other side of that artificial hill.
Concrete slabs on the beach are collapsed remains of
a battery for two fast-firing 15-pounder guns.