The metaphor for business as war is widely used, and it does have considerable value when considering strategy, tactics, capability development and resource deployment.
Marketing is a base component of this mix. It requires you to see the world, product offer, through the eyes and behavior of others, your customers, and potential customers, and in so doing, observe and understand the value proposition of alternative offerings.
So, if there is a metaphor for the competitive aspects of marketing, it is act like your enemy, do to yourself what your enemy would if they had the information, resources and capabilities you have, with the intent of defeating you.
With apologies to the original, “do unto others before they do unto you.”