This is the latest in a series of occasional articles on the shared histories of Bermuda and the United States, which celebrates the 250th anniversary of its independence this year. The articles, by Heritage Matters author Edward Cecil Harris, will run throughout the year.

As the American Civil War drew to an end in 1865 and the Bermuda economy went into recession as the role of “middlemen” traders evaporated with the disappearance of blockade runners, the new Age of Steam rounded an historic corner to save the island.

The coming event was the island-wide refortification of Bermuda to suit the era of iron ships and — dare we say in the current age — wooden men.

For a place that made its reputation and early international currency on the age of iron men and wooden (sailing) ships, it is difficult to imagine the crash to local shipbuilding and the Bermudian psyche that the Age of Steam brought upon us.

We had invented the “Bermuda Rig” method of powering sailing vessels, making our sloops the fastest craft afloat and yet used worldwide for racing yachts. In most harbours and seas around the Earth you can see our heritage, described in the early 1880s by Lady Brassey as “that peculiar rig”, as it was not yet universally known or used. The Bermuda Rig survived the Age of Steam; our shipbuilding did not, but fortunately the Civil War added essential fuel to our economic furnace.

It is axiomatic that the transshipment of European goods and war materiel into the Confederacy could not have happened with sailing ships. Steam engines made it possible to drive a vessel at speed in any direction, regardless of the cant of wind and waves.

Crossing the Gulf Stream was a piece of oceanic cake, slicing through contrary seas, whereas a sailing ship could be moved northward, against its canvas will, with that strong current and could only generally sail with the wind.

Thus, in addition to material goods, many thousand tons of anthracite were also transshipped from Great Britain to Major Penno’s new wharf “to coal” the steam boilers of the blockade runners, some engines driving paddle wheels and others revolutionary screw propellers.

In the new age, wooden hulls were being replaced by metal ones and in 1860, the launch of the iron-hulled HMS Warrior marked the transition of warships into an ironclad revolution in shipping, and consequently, armaments. Iron hulls repelled round-shot cannonballs like rain off a duck’s back and hence the pointed cylindrical “shell” was invented to penetrate the metal armour of the new types of vessels of war.

Nowhere is that revolution so aptly expressed as in our grand, if somewhat neglected, Fort Cunningham, wherein the stone (wooden) fortifications of many centuries standing were replaced with ramparts of wrought iron.

Fort Cunningham already had a claim to fame in its original construction of the 1820s, being of a “polygonal trace” design, possibly first used by the British at Bermuda.

Colonel Edward Fanshawe, Royal Engineers Corps, who saw Fort Cunningham in 1826 took the idea of the new pattern (as opposed to the “bastion trace” of the Bermuda Dockyard fortifications) to Canada and is now famous there for his design in the polygonal trace of Fort Henry at Kingston, Ontario.

Unusually, the fort here was named for its architect, Thomas Cunningham, RE, who went on to design the exquisite Fort Adelaide in black basalt (instead of white limestone) at Port Louis, the capital of the island of Mauritius.

To rearm Bermuda against the increasing strength of the now re-United States, the upper floor, if you will, of the 1820s Fort Cuningham was entirely removed. The hard Bermuda limestone masonry, likely from the Dockyard quarries, was probably reduced to “jail nuts” for the production of concrete for the new 1860s upper floor and roof.

Meanwhile, given the historic transition from timber to metal, orders were placed in Britain for the magnificent wrought iron facades for two faces of the fort, one for two guns and the other for five.

Also ordered were nine of the newfangled Rifled Muzzle Loaders, in 12.5-, 10-, and 9-inch calibres, that is the diameter of the mouth, or muzzle, of the gun. Moving away from 400 years of cast iron cannon, the new weapons were made in wrought iron, as cast iron was too weak and “gun steel” had to wait another 20 years to be invented.

When finished in the 1870s, with its straight frontages, there was no other fort like it in the British Empire, others having circular frontages or only containing iron in individual, masonry-framed gunports, like at our Alexandra Battery, called “Gibraltar Shields”.

Fort Cunningham cost an imperial fortune, to which may be added the other modified and new fortifications throughout Bermuda, against an American takeover.

Thanks to this influx of military cash (thanks also to the Yankees), the economy of the island was likely rehabilitated after the extravagances of the American Civil War period (1861-65).

Great works took place in the Far East in St George’s Parish, to the east of the City of Hamilton, out southwest in Sandys and in the extreme west, though hooking back to the northeast, at the Dockyard, as new guns were added, mostly in protection of the coasts and landing beaches.

More anti-American military data in coming weeks in The Royal Gazette!

• Dr Edward Harris is the founding executive director emeritus of the National Museum of Bermuda