How Maps Became Deadly Innovations in WWI

Advances in weaponry and cartography had deadly repercussions in World War I, which the United States entered 100 years ago today.

By the time the United States entered World War I, 100 years ago today, the conflict had been raging in Europe for nearly three years. It was to become one of the deadliest wars in human history, claiming more than 15 million lives.

Advances in military technology—including more lethal artillery and rapid-fire machine guns— contributed to the heavy toll. Maps, too, played a role. Recent cartographic innovations allowed artillery gunners to fire at targets they couldn’t directly see and aim their guns without first firing “ranging shots” that would ruin the element of surprise. Airplanes—another relatively recent invention—allowed both sides to update their maps daily with the positions of enemy troops.

The “exclusion zone” enforced by German U-boats off the coast of North America (shown on the map, top left, in this German illustration) was a major factor in drawing the U.S. into WWI.
MAPS COURTESY LIBRARY OF CONGRES

This color-coded map depicts the nations and peoples that made up the German alliance, also known as the Central Powers, during WWI.
MAPS COURTESY LIBRARY OF CONGRESS

This is a simplified illustration of the Schlieffen Plan—Germany’s strategy to launch a quick and decisive attack on France, then transfer troops by rail to the east to fight Russia.
MAP COURTESY LIBRARY OF CONGRESS

Allied tactical maps, like this one of the area around Seicheprey, France, were created from existing topographic maps (blue lines) and updated daily in red to indicate troop positions and other features of strategic interest.
MAPS COURTESY LIBRARY OF CONGRESS

This map tracks the S.M.S. Emden, an infamous German raider (see main text) that attacked Allied commercial ships in the Indian Ocean—a reminder that WWI was a truly global conflict.
MAPS COURTESY LIBRARY OF CONGRESS

This secret map made by the British Navy shows the position of German mines and progress on clearing them in August 1918.
MAPS COURTESY LIBRARY OF CONGRESS

This once classified map shows the position of troops at 11 a.m. on November 11, 1918, when the armistice ending hostilities on the Western Front was signed. A table of troop numbers shows how U.S. forces tipped the balance in the Allies’ favour.
MAPS COURTESY LIBRARY OF CONGRESS

The maps in the gallery at the top of this post illustrate these deadly innovations and other defining features of the war, including the complex networks of trenches dug by both sides and the devastating German U-boat attacks on Allied commercial ships—a major factor in drawing the U.S. into the conflict. Many of the maps, which come from the Library of Congress, were featured in a recent paper and two blog posts by Ryan Moore, a cartographic specialist at the library with an interest in military history.

Aerial Photographic Analysis by Doughboy Cartographer Willard B. Prince
MAP COURTESY LIBRARY OF CONGRESS

Throughout most of human history, people could only take aim at an enemy they could see. By WWI that had changed, thanks to powerful artillery that could fire well beyond the line of sight. But this created a new challenge: how to aim at a target that’s not directly visible.

One approach was to use spotters, who’d take up a vantage point on a hill or other elevated area and send messages back to the gunners about where their shots were landing. Radios had been invented by that point, but they were still too bulky to be widely used in the field. Instead, both sides used cable telephone lines—and human runners when the lines got cut by enemy fire.

“Someone would actually be running back and forth through the shell fire to communicate the messages,” Moore says. The gridded map below, which shows the effective range of different types of artillery pieces, is an example of the type used by spotters and gunners to coordinate artillery fire. It’s no work of art, but it represents a remarkable step in the evolution of warfare.

A Matrix of Devastation—The Gunner’s Grid
MAPS COURTESY LIBRARY OF CONGRESS

Aerial photography turned out to be another deadly innovation. Flying was still new and dangerous back then, but photos shot from above vastly improved tactical maps, Moore says. “These guys would risk their lives in these ‘flying coffins,’ as they were called, flying at 12,000 feet above the enemy with a guy leaning out the back with a camera.” That altitude was considered safe from anti-aircraft fire, but photographing crucial details sometimes required flying lower.

“They would be taking photos on a daily basis, and a whole crew of analysts would pore over the photos looking for the smallest changes in the landscape,” Moore says. To speed the process along, pilots would fly over the mapmakers’ position and drop the latest film from the plane in a cannister, along with notes on the crew’s observations. The mapmakers would develop the film in the field and update the maps with new targets.

This German map depicts the elaborate system of trenches around Verdun, in northern France in September 1918. German forces are shown in blue, Allied forces in red.
MAPS COURTESY LIBRARY OF CONGRESS

In the meantime, of course, the enemy would be on the move again. Both sides dug elaborate networks of trenches to protect their men and enable them to hold a line. At the highest levels of command, the positions of friendly and enemy troops alike would be depicted (see above). But maps given to junior officers showed only enemy troop locations, Moore says. A junior officer would already know the position of his own troops, so there was no need to put that on a map that could be captured by the enemy.

Another new technology put to deadly use in WWI was the submarine. Although military subs date back to the American Revolutionary War, the Germans’ widespread use of U-boats to attack civilian and commercial vessels was unprecedented. Several maps in the gallery depict the war at sea, including British intelligence maps of efforts to track a notorious German raiding vessel and keep their own harbours free of German mines.

Most of these maps were never seen by civilians. But after the war ended, people around the world were fascinated by maps of the treaty negotiations. Redrawing the borders of Europe was a contentious and political process—and the end result helped set the stage for World War II—but maps published around this time (like the one below) were wildly popular, Moore says.

“All sections of society were interested in these changes,” he says. “What’s the world going to look like now?”

After the war, maps of the treaty negotiations and new national boundaries in Europe were popular worldwide.
MAPS COURTESY LIBRARY OF CONGRESS

Header Image: This 1918 map depicts the deadly toll taken by German U-boats during the war. Each red dot represents a sunken ship (see below for a close-up of the British coast).MAPS COURTESY LIBRARY OF CONGRESS

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