"Network-centric warfare" is the hot concept in modern military thinking—soldiers fighting not just with weapons but within a web of sensors and computation, giving them and their commanders superior awareness of the battlefield. But the problems this approach was conceived to solve are timeless. I’m here, the enemy is out there somewhere. How do I find them? How do I keep track of them? Once the battle has started, how do I know where to move? Heck, how do I even keep track of my own people?

Long before IoT concepts littered the world, the navies of the early 20th century were among the first to take a systematic approach to answering these questions. Sail had given way to steam and European colonies had metastasized around the world. Warships were moving faster and required coordination across greater distances than ever. Meanwhile, telegraphs and radio allowed instant communications at previously unheard-of distances. All of this combined to create a revolution in how navies used information.

If you’ve played strategy games like StarCraft or Civilization or watched Cold War techno-thrillers, you’ve seen the ideal display for a commander: a map where the positions and status of friends and enemies alike are displayed and tracked in real time. This single unified picture gave those in leadership a god’s-eye view of the battlefield that could be used for accurate decision-making. But how did commanders create this picture without computers, GPS, and communications satellites? How did they keep their maps accurate and up to date?

It may be hard to fathom now, but the great naval powers of the day all had their own methods, and their use had profound effects on tactics, strategy, the design of warships, and ultimately, combat. It’s no exaggeration to say that some of the major naval battles of World War I and World War II turned not just on firepower but also on computational power.

Battlecruisers and the birth of information-centric warfare

In 1900, the British Empire was at the height of its powers and the Royal Navy ruled the waves. But the Brits had a problem. Russia and France were Britain’s most likely enemies, and they knew they couldn’t match the Royal Navy in a straight-up fight. Instead, they built armored cruisers—powerful warships that could sink anything smaller than a battleship while being much faster. In the event of war, these vessels would be set loose on British shipping lanes, posing an existential threat to an Empire held together by seaborne trade.

To deal with this threat, Britain started building its own armored cruisers, even faster and more heavily armed than the French and Russian ships. But ships on the open sea are hard to find, so Britain needed to build enough armored cruisers to station them on all of its trade routes. It was like playing whack-a-mole by buying a separate mallet for every hole, and it was rapidly becoming unaffordable. Rich as the British Empire was, it had to figure out a different strategy.

Research provided by... Much of the material in this article is drawn from a series of books by the American naval historian Norman Friedman (a former physicist!). In particular, his book Network Centric Warfare: How Navies Learned to Fight Smarter Through Three World Wars formed the foundation and initial idea for this article. It also includes the discussion of Kurita’s decision-making at Leyte Gulf. The material on Jacky Fisher and his grand strategy for British battlecruisers, as well as the British use of plotting at Jutland, were drawn from his books Fighting the Great War at Sea: Strategy, Tactics and Technology, and The British Battleship: 1906-1946. I also highly recommend his book Fighters Over the Fleet: Naval Air Defence from Biplanes to the Cold War for a detailed picture of how information and computation tied into warfare when aircraft carriers took over from battleships. Additional background information on WWI strategy and warship technology were drawn from David K Massie’s Dreadnaught and DK Brown’s series on British warship design. Of course, we also went down a few Wikipedia rabbit holes.

Enter Admiral John “Jacky” Fisher. Fisher was appointed First Sea Lord, the commander of the Royal Navy, in 1904. He is famous for his technical innovations, most notably conceiving the HMS Dreadnought, which set the standard for all battleships to follow. What’s less well known is that Fisher was appointed not to execute his ideas for turning the Royal Navy into a better fighting force, but to stop the massive growth of the naval budget.

His solution to the armored cruiser problem was another revolutionary ship concept: the battlecruiser. It would have a speed faster than any existing armored cruiser, but it would carry the same guns as a battleship. In theory, it could chase down and destroy any armored cruiser while staying out of range of the cruiser’s own guns.

The battlecruiser was so important that initially the Royal Navy only built one new battleship to try out the Dreadnought concept, but they immediately built three battlecruisers of the Invincible class. Now, battlecruisers have a controversial place in naval history that is too complicated to get into here. But one question worth raising is, why did Fisher, and anyone else, think they were a good idea? And, given the whole budget problem, how could the British start building ships that were even more expensive than the armored cruisers they were replacing?

The answer to these questions are less obvious and not as well known—because they have to do not with the technology of the ships, but with how Fisher envisioned they would be used. Norman Friedman discusses this extensively in his book Fighting the Great War at Sea: Strategy, Tactics and Technology.

If you compare a British battlecruiser to a battleship of the time, you can see a few obvious differences: fewer guns, more funnels. But there’s another, more subtle difference—the battlecruisers were each equipped with towering masts to hold long-range radio antennas. These antennas let them communicate with land-based stations from hundreds or even thousands of miles away, and they were the key to a new kind of cruiser warfare.

Fisher knew there was no way Britain could afford to build enough battlecruisers to cover all of its trade routes. But it wouldn’t need to—in addition to being a naval superpower, Britain was also an information superpower. British companies had spent the past few decades building a global network of telegraph cables and radio transmitters, meaning Britain had access to the finest communications infrastructure in the world.

Instead of dispatching his battlecruisers to the far corners of the earth, patrolling for enemy cruisers in the hopes of finding them, Fisher would wait. Reports of attacks on British shipping would be transmitted instantly back to the Admiralty (British naval headquarters) in London, and there they’d be pieced together to form a picture of the locations and activities of enemy cruisers. Then the Admiralty could direct the battlecruisers to exactly the right places to find and destroy those enemies. It was like a fire-control problem, only instead of trying to hit a ship with a gun shell, the battlecruisers themselves would be projectiles fired by the Admiralty.

To achieve his vision of a centrally controlled battlecruiser force, Fisher needed a clear picture of the threats. So he set up a top-secret room in the Admiralty building where intelligence reports and shipping news from all over the world were aggregated onto large maps that showed the positions of every friendly and known enemy ship.

This was known as the Admiralty plot. Unlike the displays you might see in a modern military headquarters (which may be updated every few minutes or seconds), these paper maps had a “refresh rate” of hours or even days. But they were nonetheless revolutionary, because for the first time in history a centralized commander could look at a representation of the world naval situation, with every friendly force and known enemy force tracked all around the world in nearly real time. The British leadership could then issue commands accordingly.

This was the innovative strategy behind the battlecruiser, and it was particularly realized in one spectacular battle during World War I.

Shortly before the outbreak of war, the German East Asia Squadron left its base in Tsingtao, China. The squadron, a crack gunnery force built around the armored cruisers Scharnhorst and Gneisenau, was led by Admiral Graf von Spee, probably the most innovative and daring commander in the Imperial German navy.

Once war was declared, the East Asia Squadron did exactly what earlier French and Russian strategists envisioned, wreaking havoc on British trade in the Pacific for months. Eventually, they crossed the Pacific and destroyed a smaller force of British cruisers off the South American coast at the Battle of Coronel. It was the worst defeat the Royal navy had suffered in over a century.

But radio reports from British merchant ships that were captured or sunk allowed the Admiralty to pinpoint the location of the German forces as they crossed the Pacific and then turned past Cape Horn.

The Royal navy dispatched the battlecruisers HMS Invincible and HMS Inflexible to the South Atlantic. There, at the Battle of the Falkland Islands, the German squadron was annihilated by the much more powerful and longer-ranged guns of the British battlecruisers. It was everything the battlecruiser had been designed to do, vindicating not just Fisher’s ships but also his information-centric strategy.

It was the high-water mark for battlecruisers. Unfortunately for their reputation, though, after that the Royal navy found itself in a very different war than the kind battlecruisers had been designed to fight. Germany, unlike France and Russia, had not decided to go for commerce-raiding cruisers. Instead they decided to challenge the British head-on, building their own fleet of battleships and battlecruisers.

These naval behemoths would eventually meet at the Battle of Jutland in 1916. There, the British battlecruisers met their doom, and that’s another battlecruiser story outside the scope of this article. What is in scope, however, is the critical, nearly decisive role that information played in that battle.

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