In this article via Task & Purpose, author Brad Hardy states that operational art is a cornerstone doctrinal concept that joint headquarters and defence forces use to plan everything from battalion-sized operations through to major campaigns. As such, he argues that its definition is so broad that it is vulnerable to losing its meaning.

The book 'The Operational Art: Canadian perspectives: Context and Concepts', edited by Allan English, Daniel Gosselin, Howard Coombs and Laurence Hickey contains a number of essays that are designed to make a contribution to professional military education.

In less than a page encyclopedia.com breaks it down for us, explaining that operational art forms a bridge between strategy, defining the political aims of a war, and tactics, fighting the battles of a war.