One of the biggest secrets of the financial crisis was disclosed Thursday when the Federal Reserve released thousands of pages of data showing heavy discount-window borrowing by foreign banks, regional U.S. banks and institutions fighting for survival.

It was the first time the Fed has given details about banks that borrowed from the central bank's oldest emergency-lending facility. Thursday's move was forced by lawsuits filed by Bloomberg LP's Bloomberg News and News Corp . 's Fox Business Network, and last year's Dodd-Frank law requires the Fed to disclose future borrowings after a two-year lag. Details of other rescue programs by the Fed were made public in December.

News Corp. owns Dow Jones & Co., publisher of The Wall Street Journal.

The disclosures include loans made by the Fed from August 2007 to March 2010. The period includes the darkest moments of the crisis, including the September 2008 collapse of Lehman Brothers Holdings Inc. Lehman's weekend tumble into bankruptcy ushered in unprecedented U.S. intervention to prop up the teetering financial markets and deepened the panic already spreading through banks and securities firms around the world.

When discount-window lending peaked at $110 billion on Oct. 29, 2008, European banks Dexia SA and Depfa were the biggest borrowers. Dexia took $26.5 billion that day, while Depfa Bank, a subsidiary of German Hypo Real Estate Group, took out $24.6 billion. In the following weeks, the banks accessed the discount window nearly daily for tens of billions of dollars.