Amazon and Walmart have been duking it out for quite some time now.

In the latest barrage against its digital-native rival, Walmart is unleashing free next-day shipping on orders over $35.

This intense shipping war is sure to be a boon for consumers.

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The battle between Walmart and Amazon is a retail rivalry for the ages.

Theirs is the tale of a brick-and-mortar chain competing with an e-commerce giant; a startup-turned-behemoth squaring off against a colossus scooping up digital-native startups.

But the ultimate winner of this showdown might just be the people chilling on the sidelines: the shoppers both companies are trying to court.

Walmart recently landed a major punch against its opponent with the announcement that it intends to roll out one-day shipping to its customers. The offering will be free for orders over $35. The move was unveiled just days after Amazon touted its new plan to slash its Prime delivery guarantee from two days to one day.

It's no secret that consumers win when businesses compete. The scramble to the top can spark companies to pursue innovation, lower prices, and top-notch dedication to customers. In the case of the retail delivery wars, that means faster, cheaper shipping all around.

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Walmart's latest barrage against Amazon is a good indicator that retail companies are hunkered down and dedicated to fighting these shipping wars. And it's not just a competition between those two giants. Target has upped its same-day delivery services with its acquisition of Shipt, and Kroger is also playing around with online delivery.

Both Amazon and Walmart are couching discussions of these retail innovations in terms of what they'll mean for customers.

Walmart e-commerce CEO Marc Lore previously told Business Insider that "shipping costs will definitely go down" as a result of the retailer's fulfillment-center-oriented approach to delivery, resulting in bigger savings for the consumer.

Amazon tweeted that its "smart" shoppers would "know the difference" between its millions of products available for "free SAME DAY delivery" across the United States and its competitors' efforts to "up their fast shipping game."

Sucharita Kudali, vice president at the market research firm Forrester, previously told Business Insider's Dennis Green that the ultimate winner of the delivery battle between Amazon and Walmart will be the shoppers themselves.

"There's still a ton of competition, and ultimately the customer wins," she said.