On Sept. 8, the federal official overseeing these arrests decreed that law enforcement agents were enforcing the Aug. 8 orders too stringently. It was evident that people were being arrested who posed no threat to the public safety. Thereafter, the arrests subsided. Still, Lincoln himself reiterated the suspension on Sept. 24, and arrests without trial continued. Overall between 10,000 and 15,000 people were incarcerated without a prompt trial. On balance, their detention almost certainly did not enhance American security nor hasten the Union victory.
In the last 140 years, America has not faced a crisis anything like the Civil War, and the power to suspend habeas corpus has mostly gone unused. Although (as I'll explain next week) the Supreme Court never definitively ruled Lincoln's suspensions unconstitutional, his actions did come to be seen as a blemish on an otherwise heroic record of wartime leadership. That disrepute into which his behavior fell just may have helped deter his successors from using such measures themselves.
In the days after Sept. 11, George W. Bush was seen conspicuously toting around a new best-seller about the Civil War, as if to suggest he were reading up on the historical lessons of wartime leadership. It would be good if he brushed up not just on our greatest president's heroics but also on his sad mistakes.
The best book on Lincoln and civil liberties during the Civil War is, as mentioned, Mark Neely's The Fate of Liberty: Lincoln and Civil Liberties (1991). James McPherson's Battle Cry of Freedom: The Civil War Era (1988) is reliable for anything Civil War-related. Dean Sprague's Freedom Under Lincoln (1965) is dated but helpful. Overviews of wartime suppressions of civil liberties include Michael Linfield's Freedom Under Fire: U.S. Civil Liberties in Times of War (1990), which is generally critical toward such suppressions, and William Rehnquist's All the Laws but One: Civil Liberties in Wartime (1998), in which the chief justice generally defends them.