Stannis Baratheon II

After the disastrous events of the First Clash, the Stormlands were lead by Stannis Baratheon II. He would be an important military leader in the Second Clash and would see himself be crowned king at the end of it. He was also known as Stannis the Cruel and Stannis the Kind, the first nickname being mostly used among Northern circles. 
== The Second Clash ==
Before the fighting started, Lord Stannis was a member of the Great Council. Alongside him in the Council were Lord Bron II and Lady Tully. When the time came to elect a new king, it was Stannis who tried to keep the council from petty squabbling and send out a message to all High Lords and Ladies of Westeros to meet at the capital to elect their new leader. When every negotiation failed and no one wanted to step up to stake a claim, Stannis pronounced that he would nominate himself to be King out of duty to the country. 
Rather than approach things peacefully, a coalition formed against the council led by Lord Haatack Stark, a man who was more Wildling than Northerner. 
The war was something that took long to commence, so Lord Stannis took it upon himself to make extensive preparations. The biggest threat was the North, a land that was rumoured to have a massive army ready to march down south. An army that barely made it past the Neck in the end.
Stannis contacted the Boltons for aid, and promised them the title Warden of the North in return for support for his Kingship, and treachery against the Starks once they started marching south. 
=== The Start of the Clash ===
The war began with much bloodshed. The Reach and the Riverlands took the blunt of the slaughter as Stannis had grossly underestimated the force he was up against. Dorne, The Westerlands, The North and The Iron Islands all had massive armies both in reserve and on the field. 
Within weeks, the Reach fell to the insurrection and was forced to join the traitors. The Riverlands were burning and the Great Council armies were being beaten at every turn. The Bolton Betrayal was a big succes however, and Lord Stark was cut off from his homeland as Moat Cailin was taken by Bolton forces.
Lord Stannis, who was determined to both fullfill his ambitions and uphold order in Westeros, had not partaken in any of the fighting at the end of the war because he feared he would be overrun by Dornish troops while he was away in the Riverlands. He even attempted an unsuccesful invasion to try and take out his Dornish opponent so he could join the fray. This ended in the desert itself defeating the invasion force and sending it back to Storm's End.
=== The Turning Point ===
Lord Stannis had enough of the war and decided that what Lord Stark had started, he should end. He made up for his lack of manpower and funding by contacting the Iron Bank, and send Sir Davos Seaworth to negotiate. He returned with the Golden Company, chests filled with coins and a big smile on his face.
Then it began.
Stannis instructed his son Lyonel to hold a riverline with a sizeable army for if the Dornish would invade and he marched with nearly 200.000 men towards the Riverlands. 
First, he took charge of the Tully garrison in Harrenhal, adding it to his army. He then had the garrison of the Bloody Gate join him forming the official Great Council United Army. With this Great Army he destroyed the Northern forces at Flint, leaving the North without a fighting force. He then prepared to finish the Clash at Riverrun were the Lannister army had stationed itself. This would have been a gruesome and long siege which probably would have prolonged the war by multiple years, if it had not been for an unlikely ally. While the Great Army was pushing towards Riverrun, they found the castle gates wide open upon arrival, unbeknownst to the defenders inside. Beric Dondarrion II had openened them, giving Stannis the chance he needed to finally end the war. 
After a relatively short battle due to overwhelming numbers the Great Army possesed, the Lannister force lay defeated at Riverrun. When word came of this defeat, the traitors surrendered and stood behind Stannis to support his claim to the throne. While the Reach was hesitant, the Riverlands fully supported Stannis aswell giving him a majority vote, which finally semented his place as King. 
== Rule Under Stannis ==
After the war, Stannis had to start making changes and desicions which would change Westeros for a long time and effects of it could still be felt in the Third Clash. 
He first had to make a change to himself, as he was a follower of the Lord of Light. He converted to the Light of the Seven in order to properly claim his crown and was soon after crowned by Bron Tyrell II in the Sept of Baelor.
Now that he was oficially recognized by both the faith and the noble houses he had to start solving the huge issues left by the war. The North had joined it's kingdom with the Iron Islands after a political marriage but the Boltons were promised the North as their prize for betraying the Starks.
What followed next is how Stannis would be forever remembered for as Stannis the Cruel in the North. To prevent another civil war with the joined kingdom, Stannis declared the Boltons traitors, stripped them of their claims to Northern territories and send out orders to hunt them down. House Bolton, now reduced to mere bandits evaded this manhunt and kept roaming the North. House Greyjoy became the new Lords of the merged Kingdom. 
For his bravery, Beric Dondarrion II was wedded to Shireen Baratheon and was given Storm's End. His Son Lyonel was given Dragonstone.
With the question of territories now resolved, Stannis needed to be reminded that the Iron Bank always get it's due. The war had cost him dearly and the debt needed to be repaid. This was however the least of his problems and was resolved rather quickly. Money needed to come to Westeros, and because it was bled dry from all-out war, Stannis ordered the Royal Fleet be converted to a Trading Fleet. This led to the founding of the Royal Trading Company, an entity solely focused on trade with Essos to bring wealth back to Westeros. He also made a tax plan called the Westeros Restoration Act which raised money for both paying back the Iron Bank and rebuilding Westeros after the war. The Royal Trading Company later made Dragonstone their homebase. Lyonel Baratheon would soon after take command of the Company alongside Davos Seaworth.
These things were standard to do as a king but Stannis his greatest act as king and the thing he would be most remembered for was his method of preventing a war which would have put Westeros right back to the state of rebellion which it was so accustomed to by now.
Back in the Riverlands, House Tully was being pushed out of it's home again. Remnants of the Trident Union started reorganzing in the wartorn kingdom so they could seize power once more. 
King Stannis choose to avoid conflict and all the money raised by the Westeros Restoration Act was being spend on improving lives for the people in the Riverlands. Instead of armed conflict, King Stannis choose diplomacy as his tool to fix this crisis and the people loved him for it. This choice prevented a long and drawnout armed conflict, gave Westeros time to rebuild and gave King Stannis his most famous nickname: King Stannis the Kind
After 19 years of peaceful rule, King Stannis passed away leaving the throne empty once again.