1. Haiti
   Spain
2. United States

Since 1248, Spain's King's Own Immemorial 1st Infantry Regiment has been serving the country. And the unit is still going strong, providing protection for the army's headquarters.

1. corps
   brigade
2. platoon

A corps is a large army unit, one that may have anywhere from tens of thousands to hundreds of thousands of troops. They are what form field armies.

1. platoon
   phalanx
2. fire team

In the days of the ancient Greeks, phalanxes were a common type of tactical unit. They'd swarm closely together with men carrying huge shields, followed by men with long pikes and spears.

1. legions
   troll hunters
2. armored cavalry

The Roman legions left a legacy of battlefield heroics. These legions were large groups of troops numbering about 10,000, and consisted of multiple flexible groups for various purposes.

1. The unit was made up of very tall men.
   They fought only against literal giants.
2. They were all, ironically, quite short.

King Frederick I of Prussia committed many resources to his Potsdam Giants unit, which was made up of Europe's tallest men. Legend has it that one soldier was around eight and a half feet tall.

1. 947th Military Police Detachment
   1st Cavalry Division
2. 101st Airborne

In late 1944, the German army launched its last major offensive on the Western Front. They nearly broke through, but the 101st Airborne hunkered down and stopped them, even though they were surrounded for a week in bleak winter conditions.

1. company
   brigade
2. platoon

Divisions may have tens of thousands of troops. They are made up of brigades, which are themselves made up of several thousand soldiers.

1. "Old Hickory"
   "Old Blood and Guts"
2. "The Big Red One"

The 1st Infantry Division uses a red "1" as its insignia. It is "The Big Red One," and it saw major action in both World Wars and beyond.

1. South Africa
   Vikings
2. Russian

In ancient times, the Vikings were feared warriors. Particularly terrifying were the "berserkers" who fought with extreme rage and skill. No one knows why they were so crazed, but some sort of substance abuse may have contributed to their blood lust.

1. 101st Airborne
   1st Division
2. 182nd Infantry Regiment

America is a new country but it does have several very old continuously serving units. That includes the 182nd Infantry Regiment, from the Massachusetts Colony. It was established in 1636. Several others in the area were formed at the same time.

1. Korean War
   Vietnam War
2. World War I

In July 1918, during WWI, the 3rd was tasked with stopping a German offensive near the Marne River. As other Allies retreated, the 3rd bravely held, earning the title of "Rock of the Marne."

1. Muslim
   Catholic
2. Mormon

In the 1840s, the Mormon Battalion made headlines by becoming the first and only religious-based unit in the country's history. More than 500 men served in this historic battalion.

1. defeated Geronimo
   won the Mexican-American War
2. marched 2,000 miles

The Mormon Battalion was ordered to march from Iowa to Southern California, a journey of more than 2,000 miles. Their efforts helped to cement America's claims to the Southwest over Mexico.

1. World War II
   Mexican-American War
2. Russian Civil War

Believe it or not, the British military dropped parachuting dogs into Europe during D-Day in WWII. The dogs had all sorts of jobs, from detecting mines to warning Allied troops to the presence ("woof!") of German soldiers.

1. Persia
   United States
2. Panama

In ancient times, the Empire of Persia maintained the 10,000 Immortals. King Xerxes used these elite soldiers as his personal bodyguards, and to menace the more common armies of his enemies.

1. Sweden
   Mexico
2. YMCA

Since 1521, Sweden's Life Guards -- formerly the Svea Life Guards -- have been serving. These men were originally chosen to act as the king's bodyguards.

1. elephants
   reindeer
2. frogs

Russian troops need reliable ways to move in very cold and inhospitable terrain. The Russian Northern Fleet Motorized Rifle Brigade -- a modern unit -- relies on reindeer to pull gear and men through icy terrain.

1. Egypt
   Guatemala
2. China

In ancient Egypt, the Medjay were an elite paramilitary force. They performed all of the most important jobs, from desert reconnaissance to protecting anything of interest to the pharoah.

1. to haunt Japanese leaders
   to confuse Axis commanders
2. to terrify superstitious German troops

In the midst of WWII, the Allies used inflatable decoys that looked like tanks and Jeeps to confused Axis commanders. This "ghost army" was moved around from place to place, effectively making the Germans believe the Allies had more vehicles than they really did.

1. They used a secret "butterfly" weapon.
   They could fly (short distances).
2. Their flag featured a butterfly.

In the Civil War, the 3rd New Jersey Cavalry was a unique unit. Its flag featured a butterfly, and the men wore funky capes with hoods.

1. Gatling guns
   swords
2. explosive cocoons

The Butterfly Boys had a crazy leader who insisted that his men fight only with swords. Mind you, the enemy was using rifles.

1. to guide Allied troops through ruined European streets
   to capture Hitler
2. to preserve works of art

During WWII, the Allies had a unit called the “Monuments Men." Their job was to pinpoint important works of art to prevent them from being bombed into history.

1. to rout Vichy French troops in North Africa
   to hunt down art stolen by the Nazis
2. to plan the invasion of Normandy

The Nazis looted museums all over Europe. When the Allies began taking back the continent, the “Monuments Men” did their best to find -- and retake -- those items from German hands.

1. 101st Airborne
   20th Bomber Wing
2. Connecticut Army National Guard

Formed all the way back in 1672, the 192nd Military Police Battalion is now part of the modern Connecticut Army National Guard. It's all-caps motto is "SKILL AND FORCE!"

1. nuclear attacks
   assassinations
2. political and psychological ops

In North Korea, the Korean People's Army Special Operation Force is a very large force dedicated to certain types of intelligence activities. That includes psychological and political manipulation meant to confuse and distract enemies … and perhaps the citizens, too.

1. Iranians
   Vikings
2. Americans

In ancient Europe, the Varangians were a group of Viking soldiers that plundered various areas and served as elite mercenaries. Military leaders would sometimes hire the Varangians and then send them in at the end of battles to crush remaining enemy resistance.

1. paralysis
   blindness
2. autism

In Unit 9900, Israel's autistic people shine in incredible ways. Officials use their ability to find tiny details on intricate maps to better understand enemy troop activities.

1. Battle of Waterloo
   Battle of Shiloh
2. Battle of Thermopylae

At the ancient Battle of Thermopylae, the 10,000 Immortals struggled to beat a few hundred Spartan troops in a narrow canyon. But the Spartans were betrayed, and an information told the 10,000 Immortals how to skirt past the Spartans and attack them from the flank.

1. American Revolution
   Gulf War
2. World War II

The Ritchie Boys were thousands of intelligence troops trained in German culture and language for secret operations in WWII. Many of the men were actual Jewish immigrants from Europe who wanted to do their part to fight the Nazis.

1. "Ye Olde Gentlemen"
   "Highlanders"
2. "Bloodsmashers"

In the Civil War, the 79th New York Volunteer Infantry called themselves the "Highlanders" as a tribute to their supposed Scottish roots. They even wore snappy kilts on the battlefield.