The Forgotten WWII Invention That Changed Simulation Forever

By Stephen Walton, Senior Curator at the Imperial War Museum

In 2014, the Imperial War Museum (IWM) received into their archived collections what to the uninformed eye looked like an unremarkable scrapbook. I had first seen it when I met Ewan Ward-Thomas, the grandson of its original compiler and owner, in a pub opposite London’s Liverpool Street railway station. The book contained a large number of documents, letters, memoranda, photographs and printed ephemera pertaining to an invention officially designated as `Apparatus, Dome, AA Training’, the brainchild and creation of Ewan’s grandfather, Lieutenant Commander Henry Christian Stephens, Royal Navy.

Military Imperative and Photography Converge

I had not previously been aware of either the Dome or its inventor. A veteran of the Battle of Jutland as a Royal Navy midshipman in 1916, Stephens pursued a civilian career as a photographer in the interwar years. These two strands of his professional experience came together after Britain again found itself at war in 1939. In this conflict, sailors, soldiers and civilians were all considerably more vulnerable to attack from the air than previously, but anti-aircraft gunnery training had remained rudimentary and inadequate to meet the new challenge. This important gap was filled by Stephens, who developed what was effectively one of the first ‘virtual reality’ training simulators.

A Training Transformation

Within his Dome Trainer, moving images of aircraft models were projected onto a curved screen for trainee AA gunners to shoot at with a weapon whose firing actions were likewise simulated, with an array of accompanying visuals and sound effects to make the total experience as realistic as possible. With 300 domes deployed across the world, Stephens' Dome became a gamechanger and the standard British AA gunnery trainer, contributing significantly to the defeat of the Axis powers in 1945. The biggest impact of Dome training was in the increasingly successful defence of Britain’s Merchant Navy convoys and their Royal Navy escorts. In the opinion of Admiral Sir Frederic Dreyer, former Inspector of Merchant Navy Gunnery, it probably saved shipping and cargoes to the value of £350 million.

Stephens' Legacy

But Stephens’ invention also had a significance far beyond the Second World War. The technology which he was instrumental in developing continued to evolve after the war, with Dome Trainers being built and used up until the 1980s and beyond. It also fed into the IMAX dome cinema and similar innovations from the early 1970s. It is difficult to imagine today’s VR revolution without the groundbreaking vision of Stephens and others in those far-off days of the Second World War, creating not just a more sophisticated type of AA gunnery training but sowing the seeds of profound technological changes that are shaping our lives and those of generations to come.

IWM’s archives and exhibits include many wartime technological ground breakers, among them Wernher von Braun’s V-2 rocket, which led to the Moon landings and the exploration of space. Henry Stephens’ unassuming scrapbook takes its place alongside all of these, less obvious and less spectacular, but no less important to our understanding of today’s world.

About the Imperial War Museum

Founded in 1917, the IWM is the UK's leading authority on conflict and its impact on people's lives. With collections spanning art, photography, personal testimony and objects, the museum explores the causes and consequences of war from the First World War to the present day across its sites including IWM London, IWM Duxford, the Cabinet War Rooms and HMS Belfast.

To learn more about this fascinating story, "The Secret Dome" by Stephens’ grandson Ewan Ward-Thomas has recently been published and can be found at Pen and Sword Books.