While modern warfare seems to be focused more on firepower than manpower, the world’s superpowers still maintain large fighting forces. Both China and Russia have a standing army of over 3 million troops, while the United States has a military that includes over 2 million service members.

While this is an impressive amount of manpower, it still pales in comparison to some of history’s largest armies. Here are the largest militaries that the world has seen throughout history.


Statues of Persian warriors in line
Credit: FrankvandenBergh/ iStock

One of the greatest armies of the ancient world was put together by Cyrus the Great around 600 BC. The Persian emperor built an army of 500,000 men – the largest the world had yet seen. That army would help Cyrus the Great expand his empire to the “four corners of the known world.” At one point, almost half of the people in the world were a part of the Persian Empire.

The Persian army would remain the high-water mark for the largest armies ever assembled for centuries. Even the Roman army, which conquered nearly all of Europe, would not exceed 450,000 troops at its largest.


Mongolian horse riders take part in the traditional historical show of Genghis Khan era in Ulaanbaatar, Mongolia
Credit: Dmitry_Chulov/ iStock

The Mongol Horde, as it was called, was the first army to reach 1 million troops. The Mongol army swept across Asia, conquering nearly the entire continent in a little less than a century, along with a large portion of eastern Europe.

While the scope and the speed of the Mongolian conquest was unmatched, the Empire was not built to last. It took only another century for the Mongolian Empire to fall into a patchwork of warring factions.


Napoleon ordering the II Corps into action on 12 October 1805
Credit: Pierre-Claude Gautherot/ Public Domain

Modern industrialization and organization allowed for the size of armies to increase dramatically. During the reign of Napoleon, the French army used conscription to field an army with more than 2 million members.

The French Grande Armee swept across Europe in an unstoppable fashion and established an empire that controlled most of continental Europe. However, Napoleon’s dramatic defeat at Waterloo marked the end of the largest army yet seen in Europe and the French Empire.


Army tanks on a street in Russia
Credit: Mordolff/ iStock

The techniques that had set the stage for France to build such an impressive fighting force were used on an even larger scale in Russia during the lead-up to World War I. By the time Franz Ferdinand was assassinated the Russian army had 6 million troops at the ready.

While Russia entered the war with the largest number of troops, the French ended it with even more. By the time the war was resolved in 1918, the French had put more than 8 million troops on the battlefield.

United States

Silhouette of soldiers and helicopters
Credit: guvendemir/ iStock

The United States lays claim to the largest army ever seen in the history of the world. This force was assembled and deployed during World War II. When the United States military was at its largest, there were more than 12 million individuals enlisted in the different branches of the United States armed forces.

While the United States had the largest military during World War II, other nations weren’t far behind. The German army during World War II reached 11 million soldiers, as did the Russian army. And while the standing Russian force never exceeded that amount, it is worth noting that some historians place the total number of Russian military losses to be as high as 26 million.

The largest armies today

Soldiers standing in a row, photo of their legs and boots
Credit: Dzmitry Ryshchuk/ iStockPhoto

Today the largest armies are found on the Korean Peninsula. North Korea keeps a fighting force of over 9 million active troops while South Korea maintains a force of 5 million. While tensions remain high between the two countries, they have so far managed to avoid another significant armed conflict.