argues that "for years" Lincoln's letter has been misread as "Lincoln only wanted to save the Union." However, within the context of Lincoln's entire career and pronouncements on slavery this interpretation is wrong, according to Striner. Rather, Lincoln was softening the strong Northern white supremacist opposition to his imminent emancipation by tying it to the cause of the Union. This opposition would fight for the Union but not to end slavery, so Lincoln gave them the means and motivation to do both at the same time. In his 2014 book, Lincoln's Gamble, journalist and historian Todd Brewster asserted that Lincoln's desire to reassert the saving of the Union as his sole war goal was in fact crucial to his claim of legal authority for emancipation. Since slavery was protected by the Constitution, the only way that he could free the slaves was as a tactic of war—not for its own sake. But that carried the risk that when the war ended, so would the justification for freeing the slaves. Late in 1862, Lincoln asked his Attorney General, Edward Bates, for an opinion as to whether slaves freed through a war-related proclamation of emancipation could be re-enslaved once the war was over. Bates had to work through the language of the Dred Scott decision to arrive at an answer, but he finally concluded that they could indeed remain free. Still, a complete end to slavery would require a constitutional amendment. But a constitutional amendment has to be ratified by three-fourths of the states. There were too many slave states and not enough free states for a constitutional amendment to be ratified, so even as he was preparing to issue his Emancipation Proclamation he proposed a series of constitutional amendments that would make it easier for the federal government to pressure states to abolish slavery on their own, including compensation, a gradual timetable for abolition, and subsidies for blacks willing to colonize themselves outside the United States. None of those constitutional amendments came close to passage. But by 1863 Lincoln had other ways of pressuring the state to abolish slavery: By refusing to return slaves who escaped from loyal masters in loyal states, and by enlisting slaves from loyal states into the Union Army with the promise of emancipation, the Lincoln administration systematically undermined slavery in many of the Southern states. Lincoln had begun pressuring the border states to abolish slavery in