At the heart of Game of Thrones are two prevailing themes, namely the battle for control of the Seven Kingdoms and the Army of the Dead's southward march. What both of these themes have in common is their reliance on military forces for survival, whether that be in order to survive the onslaught of the White Walkers or to unseat the sly Queen Cersei from the Iron Throne.
We have already seen some epic battles being fought across the continents of Westeros and Essos with a diverse range of armies in action, each with their own unique weapons and fighting styles. What remains to be seen is who of these formidable forces will have the most influence come The Last War at the climax of the series?
The southernmost kingdom of Westeros, Dorne is estimated to have an army equivalent in size to that of the Vale and the north; which is particularly substantial for one of the less populated regions of Westeros.
What the Dornish have to their advantage is a unique fighting style whereby they make use of whips and spears, which most Westerosi don't have experience fighting against. This is probably why Ser Jaime and Bronn came off second best when confronting the Sand Snakes, with Ser Bronn being poisoned and Myrcella recaptured.
9 Second Sons
This is one of the numerous sellsword companies in Essos which provides its services to the highest bidder. Originally under the control of two captains and their lieutenant Daario Naharis, this 2000 soldier-strong army of brutish warriors were the ones defending the city of Yunkai when Daenerys came to liberate the city's slaves.
So great was the threat of the Second Sons, even against Daenerys' Dothraki and Unsullied troops, that Daenerys and her advisors agreed to rather ask them to join her forces for a higher price than they are already paid. Daario Naharis then murdered the two captains, effectively putting himself in charge of the army, and pledged his allegiance to Daenerys' cause.
8 Lannister Army
The overwhelming victors in the Battle of Blackwater Bay against Stannis Baratheon's forces, this army has been at the heart of the Lannister's retention of power as well as their grip on the Iron Throne.
They were instrumental in the defeat of Robb Stark's army from the north, and also defeated the army of House Tyrell in their fortress in Highgarden, thus bringing that house into extinction. Their only decline came at the hands of Daenerys' Dothraki hoard, for whom they proved no match in an open field.
7 Knights Of The Vale
An incredibly strong force of heavily armored knights on horseback, this army has protected the sovereignty of House Arryn in the mountainous region of The Vale for generations. They are also regarded as the first true knights in Westeros.
This army is predicted to number of 10 000 knights, and was instrumental in Jon Snow's victory in the "Battle of the Bastards". Due to entering this battle as well as the War of the Five Kings late on, they have retained most of their numbers, unlike the Lannister forces.
6 Army Of The North
After Jon Snow's resurrection, he regathered his allies and traveled southward to reclaim his home at Winterfell. In preparation for this feat, he and Sansa spent much time rallying together Tormund Giantsbane and his wildling forces as well as Stark bannermen such as House Mormont and House Hornwood.
After retaking Winterfell, Jon increased his army's size even further, adding the Knights of House Arryn who came to his army's aid in the battle and even those who betrayed House Stark such as House Umber and House Karstark.
5 Iron Fleet
This is the fleet of ships commanded by House Greyjoy of the Iron Islands, and has been regularly used for raids on the mainland as well as fullscale war.
With Euron Greyjoy murdering Balon and taking over as ruler of the Iron Islands, Yara Greyjoy decided to escape with the best ships in the fleet, prompting Euron to order the building of new ships. This resulted in a deadly fleet that defeated Daenerys' Dornish and Ironborn allies as they left Dragonstone, and later the Targaryen ships carrying Unsullied forces, leading to the capture of Missandei and death of Daenerys' dragon Rhaegal.
4 Golden Company
Like the Second Sons, this is yet another company of sellswords hailing from Essos. They are considered the greatest mercenary army in the world, which is why Cersei made the decision to hire them for the war to come, particularly since the Lannister army was wiped out by Drogon and the Dothraki.
They are reported to be 20 000 soldiers strong, and also make use of horses and elephants in war. Furthermore, unlike other mercenary forces, the Golden Company are known to be well organized and quick to assemble, and have a reputation for never breaking a contract.
With their unwavering reputation of being the most disciplined and skilled soldiers, members of the Unsullied are trained since birth to be warriors. It is for this reason that Daenerys traveled to Astapor to purchase 8000 Unsullied.
These Unsullied proved invaluable to Daenerys, helping her to liberate the cities of Yunkai and Meereen, defeating the Lannisters at their fortress of Casterly Rock, and even helping defeat the White Walkers.
These rugged warriors hailing from the blistering hot dessert of Essos are famous for their distinct war cries, riding into battle on horseback and use of arakhs, a type of curved sword. More importantly, they have a reputation for being the most dangerous warriors to face in open battle.
Daenerys' khalasar has successfully assisted her in battles across both Essos and Westeros; they are responsible for aiding her in Qarth, Yunkai, and Meereen, as well as decimating the Lannister army and assisting in the destruction of the White Walkers.
1 The Army Of The Dead
While the Night King and his army of White Walkers have been defeated, they remain some of the most feared and dangerous foes throughout this series. They proved their deadliness in battles such as the one at Hardhome, and are able to turn their victims into soldiers in their army, thus constantly growing their forces.
So large was the White Walker threat that effectively every Wildling abandoned their home in favor of traveling south of the Wall, which itself was destroyed by these frightening creatures. Eventually, it took the combined efforts of Jon's and Daenerys' forces (which themselves included the Dothraki, Unsullied, and Army of the North), in order to extinguish the threat of the Night King's army.