Why was the country in such disarray before Merlin emerged

The country was in such disarray because rivals battled in order to have the chance to be the next ruler when "Uther Pendragon" died.

Explanation:

Merlin is an important character in the legendary story about "King Arthur and his Excalibur." He was King Arthur's most trusted friend who was also a magician.

Uther Pendragon was a King of sub-Roman Britain. He's also considered as the father of King Arthur (through an illegitimate conception aided by Merlin). When he died, many battles emerged owing to the fact that they wanted to be crowned as the next ruler. The chaos was seen to have no end, unless a King would be crowned.

Merlin and the archbishop came to terms that whoever pulled the sword, which was known as "Excalibur," would be fit to be the King. Then came Arthur who pulled the sword and thus, he was dubbed as the next king. The king who placed an end to the chaos.