Aubrey McClendon, the chief executive officer of Chesapeake Energy, saw a chance in 2007 to join the pantheon of 19th-century oil titans, such as John D. Rockefeller and Ludvig and Robert Nobel, the Swedish brothers who once dominated Russia's oil industry.

"When you look at the sweep of history in this industry, those who move first to lock in big new acreage positions when technology changes emerge as the winners," McClendon says.

The billionaire co-founder of one of the largest natural-gas companies in the United States agreed to quietly buy 1 million acres of oil leases in Eastern Wyoming to stake a claim to more than 5 billion barrels of oil trapped beneath the Powder River Basin.

McClendon won the land grab, but his ambitious bid to dominate the American oil rush may cost him his job and his Oklahoma City-based company. The secret deal McClendon struck with an outside petroleum engineer, Ronnie Irani, helped kick off a five-year buying binge that spanned the U.S. and pushed Chesapeake's debt to a crippling $12.6 billion. The company has put as much as $20.5 billion in assets on the auction block to fill a gaping cash shortfall.

As Chesapeake careens toward financial ruin, corporate-governance scandals have shattered investor confidence in McClendon's leadership. In April, the board said it was reviewing McClendon's personal ventures with Chesapeake financiers.

In May, the directors said they would name a new chairman to replace McClendon and disclosed that the Securities and Exchange Commission had opened an informal inquiry. Shareholders have sued. McClendon apologized to investors in May.

Corporate raider Carl Icahn demanded more. In June, after amassing a 7.6 percent stake, Icahn forced Chesapeake to replace four of its nine directors with people picked by him and Southeastern Asset Management, Chesapeake's largest shareholder.

"Aubrey was swinging for the fences," says Terry Whitaker, a longtime Wyoming oil man who once owned some of the acreage Chesapeake bought in the Powder. "That's what a wildcatter does. And most wildcatters die broke."

The very acreage McClendon so prizes has undermined Chesapeake's efforts to dig out of debt. Chesapeake expects to spend up to $7 billion this year uprooting rigs from natural-gas prospects and redirecting them to more lucrative oil fields.

Paying for its drilling program has become tougher as natural gas, which accounted for 81 percent of Chesapeake's sales volume last year, fell to its lowest price in a decade in April.

McClendon, who is a minority owner of the Oklahoma City Thunder NBA team, also bet his own fortune in deals that entangled the company in his private financial empire. He used a perk that gave him a 2.5 percent stake in Chesapeake's wells as collateral for massive personal loans.

He relied on some of the same lenders, investors and advisers who have been instrumental in Chesapeake's expansion.

In April, McClendon revealed that he had borrowed $846 million as of the end of 2011 to pay his slice of Chesapeake's drilling costs. McClendon has also leveraged his extensive wine collection, his fleet of vintage boats and his share of future oil and gas production, property records show.

"The funny thing is that I don't consider myself a gambler at all," McClendon says. "I think a gambler is somebody who just closes their eyes and rolls the dice. And we don't do that." McClendon spoke for this story on April 21, and has since declined to comment.

McClendon was born into an oil family.

After graduating from Duke with a bachelor's degree in history, McClendon bought oil acreage to flip to larger companies. His toughest competitor was Tom Ward. Tired of bidding up prices on each other, McClendon and Ward in 1989 formed Chesapeake with just $50,000.

In the early 1990s, McClendon and Ward spotted the potential of unconventional natural-gas reservoirs, vast layers of rock rich with trapped hydrocarbons that were just beginning to open to development because of advances in technology.

Chesapeake went public in 1993 at $1.33 a share. By mid-1996, the stock had pushed above $30.

Then the company's key venture, a natural-gas prospect called the Austin Chalk straddling the Texas-Louisiana border, fell short of expectations. Shares plummeted to 75 cents in 1998. He and Ward tried to sell the company.

Finding no buyers, they began borrowing to acquire new prospects.

By the end of 2006, Chesapeake had amassed more than 11 million acres, a backlog of 26,000 drilling sites and $7.37 billion in debt.

In early 2007, under pressure from shareholders to make the investments pay, McClendon declared the land grab over and promised to turn Chesapeake's focus to getting the gas out of the ground. Instead, he kept spending, persuaded that Chesapeake had to find oil to survive.

To camouflage their growing position in the Powder from competitors, Chesapeake and Irani bought land through third-party brokers, naming the project after "The Prize," Daniel Yergin's sweeping chronicle of the race to control the world's oil. In February 2007, Irani paid as little as $11 an acre at a federal auction.

As word of Chesapeake's involvement leaked out, bids climbed as high as $910 an acre by that December.

In March 2008, Chesapeake announced five new oil prospects, ranging from 100,000 to 1 million acres, in four states. On July 2, 2008, as oil and gas prices surged, Chesapeake's shares reached a record $74.

Then came the crash. The global financial crisis dragged Chesapeake's shares below $30 in October 2008 while the company's capital spending accelerated to a record $7.3 billion in the third quarter.

That month McClendon, who had been buying Chesapeake stock with borrowed money, was slammed with a massive margin call that forced him to sell almost all of his 5.8 percent stake in the company, SEC filings show. Chesapeake didn't disclose the names of the lenders or the amounts of the loans.

The cash crunch brought Chesapeake's land acquisitions to a screeching halt. By the second quarter of 2009, the company's spending dropped to $1.06 billion, company records show.

Then, in August 2009, the Prize Project struck oil near Douglas, Wyo., producing as much as 900 barrels a day. Chesapeake's buying spree resumed. By the third quarter of 2010, debt had grown to $10.8 billion.

Concerned about the company's rising burdens, Icahn amassed a 5.8 percent stake in December 2010 and pushed Chesapeake to cut costs and pay off debt.

Chesapeake sold a third of the Prize Project in February 2011 for about $4,750 an acre to China National Offshore Oil Corporation, which helped the company whittle its obligations to $9.07 billion by March 2011.

Icahn sold his shares, and Chesapeake's efforts faltered. In May, Icahn once again got involved, disclosing that he owned 7.6 percent of the company.

Icahn and Southeastern in June gained sway over the board, and Chesapeake named former ConocoPhillips Chairman Archie Dunham to lead its board. Icahn didn't return a call seeking comment.

Irani says his investors have been pleased with results in the Powder, where the best wells have produced up to 1,450 barrels of oil equivalent a day.

Shareholders someday will appreciate his vision, says McClendon.

"I'm paid by our shareholders to be a leader, not a follower," McClendon says. "If I wanted to always do the most popular thing, then I'd be a follower."