Secret Weapons

1916. The war has changed course. Now the weapons are changing with it.

Beneath the North Sea, a new kind of battle is being fought.

Britain's secret Herbert Programme has transformed its experimental underwater Chariots into the formidable H-2-a longer-ranged, better-protected machine capable of operating for hours behind German defences. Petty Officer Thomas Mercer and his fellow riders can now penetrate waters once considered unreachable, striking supply ships, swept channels and naval installations before disappearing into the darkness.

But Germany has an answer.

Professor Ernst Voller's Nixe II has been designed according to a very different philosophy. German riders do not need to travel farther than the British.

They need to hide better and strike first.

Among wrecks, mine anchors and depressions in the seabed, Kapitänleutnant Matthias Schmidt creates a deadly network of underwater ambush positions specifically designed to hunt Mercer and the H-2. Soon the machines are no longer the only weapons. Both sides arm their riders with compact personal spearguns, turning encounters beneath the North Sea into terrifying contests fought at distances measured in yards.

Meanwhile, another British secret is about to emerge.

On the Somme, rumours spread of enormous tracked machines hidden behind the name "water carriers." When Britain's first tanks finally crawl across the battlefield, engineer Dawson recognises something others have missed. The tank and the underwater rider may fight in completely different worlds, but their designers are solving many of the same problems: armour, weapons, breathing, electrical systems, mechanical reliability-and keeping a man alive where no man should be able to survive.

With Winston Churchill still driving innovation from the Admiralty, Britain's two most secret engineering programmes are reluctantly brought together.

What begins as suspicion becomes something far more dangerous.

Cross-pollination.

Tank engineers learn from the Herbert Programme's breathing systems and waterproof electrical equipment. Dawson discovers new approaches to armour, redundancy and modular construction. Then one simple suggestion changes the possibilities of underwater warfare completely.

If an H-2's batteries can be replaced rather than recharged aboard its carrier submarine...

why must the rider return to the submarine at all?

As Britain prepares to establish secret supply stations on the seabed and Germany turns its coastal waters into an underwater hunting ground, the technological race enters a new phase.

And when Mercer is thrown from his damaged H-2 and finds himself facing an armed German rider among the wreckage on the seabed, the enormous war raging above suddenly becomes brutally small.

No battleships.

No submarines.

No torpedoes.

Just two men in black water, trying to find each other first.

Secret Weapons is the next action-packed instalment in the Changed Course alternate-history series-a story of invention, rivalry and the hidden arms race that could have transformed the First World War.

Perfect for readers of alternate military history, First World War fiction, naval warfare, submarine thrillers and historically grounded technological what-if stories.