Human Realms

The Human Realms were a collection of human City-States. Each independent with its own government, laws, culture, and armies. The Human Realms were in constant competition between each other. Wars were waged between citizen militias, professional soldiers and hired mercenaries. Most of these wars ended with the transfer of some farmland, the payment of tribute or concession of trading rights. It was exceedingly rare that a city itself was conquered, and in these rare cases the invaders usually installed a new local government and then left. Occupation was seen as dishonourable and not the right way to conduct a war.
=== Divine Magic ===
While the humans were not the first ones to worship the divine nor the first ones to build institutions around the gods, they had the largest and most active pantheon of the five ancient races. 
In their many churches, the human clergy discovered how to harness the powers of the divine, learning how to use divine magic. Soon soldiers were accompanied by clerics, paladins, angels, and saints. 
While the Human Realms generally worshipped all the gods in the Human Pantheon, each city had their own favoured patron god or goddess, said to represent and protect the city.
=== Human Alliances ===
While the first human cities were isolated governments are fought alone, overtime they forged alliances and alliances, usually sealed through marriage. While this had a stabilizing effect in the short term and fewer wars were fought, it meant that the wars that did break out were no longer simple regional disputes. They started to involve a couple, and then dozens of cities on each side.
Meanwhile, the human compatibility with other races such as the dwarves and the high-elves gave them access to many secrets and trading partners that would enrich their realms. Dwarves would come to live in human towns to man the forges, and once retired, their half-dwarven offspring would take over the forge. Similarly, many high-elves moved to the courts of the human realms to work as advisors, educating the humans in the ways of arcane magic. Their half-elven offspring, due to their apparent beauty, were often used as diplomats or marriage proposals to other cities.
=== The War of the Five ===
Initially, the war that would eventually escalate to the War of the Five seemed to be a dispute between the dwarves of Aul-Duroth'Tahr and the Shortfolk of Eromir Gnoa. The human realms showed little interest in the conflict, continuing trade with both sides.
When one of these trade convoys was captured by the dwarves during the Battle of Holinsted, the dwarves, assuming the city of Tralua, from which the convoy originated, to be supporting the shortfolk sent a host to the city. The dwarven host, using a night attack and siege engines, then stormed the city and abducted Princess Harphoria of Tralua and brought her back to Aul-Duroth'Thar, seeking to blackmail the city to stop its trade with the shortfolk.
Outraged about this event, the city of Tralua called in its allies to fulfil their obligations. Those allies called theirs, and through a cascading wave of alliances, the entirety of the Human Realms entered the war. Just now hearing news of the destruction of their trade caravan, the humans thought the shortfolk had purposely let the dwarves take the caravan to tempt them to war and countless human armies marched against the dwarves and the shortfolk.