Like almost every president who preceded him, Lincoln's actions at the time were somewhat controversial. Some of his most controversial decisions might actually be considered now to be abuses of the Presidential power.
When you find that you need to amend a tax return, you need to make sure the statute of limitations on filing one hasn't run out. The statute of limitations, or time allowed for the action, on getting a refund from an amended tax return is three years.
Once you file a return, the IRS has three years from the time the return was filed (or, April 15th of the year in which you file, if it is filed early) to conduct and complete an audit.