"We are at war."

"We will do whatever it takes to protect our turf."

Them's fighting words for sure, and you might think they come from Iraq or some other top-of-mind battlefield. But you'd be wrong. They were uttered by Home Depot's (NYSE:HD) chief financial officer, Carol Tome, regarding the company's biggest rival, Lowe's (NYSE:LOW).

What's Lowe's up to? It's encroaching even more into orange territory. In this case, the movement is into Home Depot's own backyard and home base, Atlanta.

A lengthy article in the Atlanta Journal-Constitution details the battle, pointing out that while Lowe's has some smaller stores in metro Atlanta, until recently its mega-stores were being built in outlying suburbs. Just as Home Depot is building more stores in metropolitan regions these days, so is Lowe's. (Within a few months, for example, Home Depot will open its first two stores in midtown Manhattan.)

The two new Atlanta Lowe's "big-box" stores will each sport more than 130,000 square feet, and are viewed, at least in part, as representing psychological warfare with their top competitor. Lowe's management explained that decisions about where to locate new units are based on location and expected traffic. (Interestingly, it seems that 74% of Lowe's stores are within 10 miles of a Home Depot. And one of the two new stores is just a parking lot away from one.)

Twenty-five-year-old Home Depot, with its 1,654 stores in 50 states and annual revenues nearing $60 billion, is the No. 2 retailer in America, behind Wal-Mart (NYSE:WMT), and is the world's largest home-improvement retailer. Lowe's is the second-largest destination for do-it-yourselfers, with 932 stores in 45 states and annual revenues topping $25 billion.

These two companies have been terrific investments for savvy capital allocators. If you're thinking of investing in them yourself, do some research first. Peruse their websites for corporate information, and study their annual and quarterly reports. Perhaps start with some Fool articles, such as Home Depot Nails It, Lowe's Q3 Raises the Bar, and our Dueling Fools on Home Depot vs. Lowe's.

Neither stock seems dirt cheap. Lowe's is trading at a price-to-earnings (P/E) ratio of about 25. For context, Hoovers.com shows its 10-year P/E range as being between 14 and 43. Home Depot's P/E is about 20, which is somewhat near the low end of its 10-year range of 13 to 70. (The low of 13 was hit in the past year.)

Which home-improvement retailer has the upper handyman? See what Fools are saying on the Lowe's and Home Depot discussion boards.