Question

why was kannauj the reason of the war​

Answer 1

Answer :-

Generally The Tripartite struggle began with the defeat of Indrayudh at the hands of Gurjara-Pratihara ruler Vatsaraja. The Pala ruler Dharampala was also keen to establish his authority at Kannauj , giving rise to a struggle between Vatsaraja and Dharampala.

This was the main reason of conflict.