Jamieson, Fausset and Brown on 2 Chronicles 22:3-4

3-4. his mother was his counsellor ... they were his counsellors--The facile king surrendered himself wholly to the influence of his mother and her relatives. Athaliah and her son introduced a universal corruption of morals and made idolatry the religion of the court and the nation. By them he was induced not only to conform to the religion of the northern kingdom, but to join a new expedition against Ramoth-gilead (see 2Ki 9:10).