By releasing 17 documents seized last year from Osama bin Laden's compound in Abbottabad, Pakistan, the U.S. government has supplied a needed corrective to the bunkum that has passed for analysis throughout the war on terrorism's first decade. For too long, government officials and pundits alike have made extravagant and incorrect claims about the weakness of al Qaeda and the irrelevance of its founding leader.

Americans were repeatedly told that al Qaeda had ceased to exist as an organizational entity, that it had become...