The War of The Five Kings is still in progress. As of 300AC.
The war started in 298AC (two years ago). Although it is considered that the war is ongoing, the main part of the war is considered to have ended in 300AC. There is no official ending of "Phase I", but it can be concluded that the first phase of the war ended with The Purple Wedding. The second phase however is ongoing.
The O.G. Five
As you know, the original five belligerents were:
- Robb Stark:
- Stannis Baratheon:
- Felt the Throne was his by rights
- Joffrey Baratheon:
- Felt the Throne was his by rights
- Balon Greyjoy:
- Wanted freedom for the Iron Islands, so that they could rape, pillage and be total douche-bags in peace. Also wanted to annex The North, because, why not?
- Renly Baratheon:
The War of The Five Kings isn't necessarily defined by the number of kings, especially given that there were never actually exactly five kings at the same time1; it's defined by their "cause".
Causes
Stannis hasn't given up, he very openly hasn't accepted defeat and hasn't made peace2. He's currently working his magic against the Boltons in The North, believing that he must first save the Kingdom to win The Crown.
The Greyjoys haven't abandoned their cause either. Even after the death of Balon Greyjoy a new king is elected in a Kingsmoot. In fact, after electing a new mental case as king, they increase their scope slightly and decide to take over all of Westeros.
Daenerys is still threatening to return with her dragons and stuff. She's taken a small break to go on holidays with Drogon and hang out with Khal Jhaqo.
- Threat... Umm, we'll see.
Because of the above, the Iron Throne has had to continue their campaigns against the pretenders.
Entering Phase II
No, really, we've entered Phase II. There are "new hostilities" which have re-ignited the War of the Five Kings. The new belligerents are:
Major events include:
When will it end?
There are many factors playing upon this clash of kings (lol, get it?). The main one being that Winter is Coming, and it has been geared to be a long winter, most probably followed by a Long Night. The threat of the Others is real, and will cause all these idiots to wake up and face the threat! (hopefully)
1. Renly died before Balon crowned himself.
2. He even jailed and later burned his Hand and brother-in-law (Alester Florent) for attempting to make peace behind his back.