The folks at FactCheck.org found more than 18,000 references to this supposed Lincoln quote. Just because Mr. Gaffney is 18,001 doesn't make him correct.
I wrote to Mr. Gaffney at the info email addy at the Center for Security Policy:
I read with interest your recent op/ed piece in the Washington Times. You opened with a quote, supposedly from Abraham Lincoln? Are you certain it was Lincoln? From my wanderings on the Internet, I've learned that this was likely by J. Michael Waller (see http://www.iwp.edu/faculty/facultyID.12/profile.asp) as reported by FactCheck.org (see http://www.factcheck.org/article415.html). I have been unable to find any primary or academic secondary source showing the quote is an accurate Lincoln quote.Feel free to join in. I wonder what the Times will say.
If this is, indeed, the case, you might want to consider a retraction, or at least a correction. You can certainly believe that "Congressmen who willfully take actions during wartime that damage morale and undermine the military are saboteurs and should be arrested, exiled, or hanged," but to attribute it to one of America's stalwarts, when he didn't actually say it, is improper, at the least.