The Amazon vs. Wal-Mart war is heating up!

According to USA Today, Wal-Mart announced it will have a huge sale on Wednesday on the heels of Amazon's recently announced "Prime Day." Wal-Mart announced the sale will take place on July 15, the same day Amazon will have its sale. Starting today, Wal-Mart lowered the threshold for free standard shipping with online purchases from $50 to $35, and the $35 minimum order policy will remain in effect for at least 30 days.

Amazon will kick off its sales event on Wednesday for members of its $99-per-year Prime service. On Wednesday, however, Amazon is offering free 30-day Prime memberships for those who want to take advantage of the huge sales day.

In a blog posted by Wal-Mart, it explained why it's having the sale: "We're standing up for our customers and everyone else who sees no rhyme or reason for paying a premium to save."

Neither Amazon nor Wal-Mart has released the details of prices or what items will be on sale, but Wal-Mart spokesperson Ravi Jariwala took an even more direct swipe at Amazon and Prime when he told USA Today, "We just don't believe you should pay a fee to get a better price."

To celebrate its 20th anniversary this week, Amazon is also planning to offer sales as often as every 10 minutes, and the company said the day would be "filled with more deals than Black Friday."

WalMart.com CEO and President Fernando Madeira criticized Amazon for having its sale exclusively for Prime members.

"We've heard some retailers are charging $100 to get access to a sale, but the idea of asking customers to pay extra in order to save money just doesn't add up for us," Madeira said.