Here's a short story:

Infantry is the general branch of an army that engages in military combat on foot. As the troops who engage with the enemy in close-ranged combat, infantry units bear the largest brunt of warfare and typically suffer the greatest number of casualties during a military campaign. Historically, as the oldest branch of the combat arms, the infantry are the tip of the spear of a modern army, and continually undergo training that is typically more physically demanding and psychologically stressful than that of any other branch of the combat arms. Common representations of infantry fighting forces include the U.S. Army Infantry Branch, U.S. Marine Corps Infantry, Royal Canadian Infantry Corps, Infantry of the British Army, and the Royal Australian Corps of Infantry, infantry of the Norwegian Army. 

Infantry can enter and maneuver in terrain that is inaccessible to military vehicles and employ crew-served infantry weapons that provide greater and more sustained firepower. The transport and delivery techniques of modern infantrymen to engage in battle include marching, mechanised transport, aerial drop by parachute or by air assault from helicopter and amphibious landing from the sea. 

In English, the 16th century term infantry (ca. 1570s) describes soldiers who walk to the battlefield, and there engage, fight, and defeat the enemy in direct combat, usually to take and occupy the terrain. As describing the branch of the combat arms, the term "infantry" derives from the French infanterie, which, in turn, is derived from the Italian fanteria and ultimately from the Latin infantera; the individual-soldier term infantryman (1837) was not coined until the 19th century. Historically, before the invention and the introduction of firearms to warfare, the foot soldiers of previous eras—armed with blunt and edged weapons, and a shield—also are considered and identified as infantrymen. (End of story)

Provide your best guess for the following question. Give ONLY the guess, no other words or explanation.

For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>

Here are a few examples of questions and answers:

Question: how many infantry fighting forces in the story are named?
Guess: Six

Question: which one was listed first?
Guess: U.S. Army Infantry Branch

Question: which one was last?
Guess: infantry of the Norwegian Army

Question: how many countries do the forces in the list serve?
Guess: Five

Question: which country has two units listed?
Guess: the U.S

Question: when does the definition of the term date from?
Guess: 16th century

Question: any specific year?
Guess: no

Now answer the following question in the same format.

Question: what is the definition?

the general branch of an army that engages in military combat on foot.