William H. Seward served as Lincoln's Secretary of State. Despite having disagreements, Seward was instrumental in advising Lincoln on both domestic and foreign affairs. He is also highly credited with keeping European nations out of the Civil War, and helped navigate the Trent Affair with Great Britain.
Edwin M. Stanton served in Lincoln's cabinet as Secretary of War. Stanton distrusted Lincoln, especially his actions leading up to the Civil War. He is noted for his insight and organizational abilities, despite his clashing with President Lincoln. After Lincoln's assassination, Stanton went on to serve under President Andrew Johnson.
Under Lincoln, Salmon P. Chase served as Secretary of the Treasury. Chase, who supported Lincoln as a presidential candidate, helped initiate the National Banking Act which allowed the creation and circulation of greenback dollars in order to fund war efforts. Chase also established the Bureau of Internal Revenue, which would later become the Internal Revenue Service.
Andrew Johnson served as Lincoln's vice president in 1864, helping balance the ticket for Lincoln's reelection bid in that same year. Johnson was a Southern democrat from Tennessee, but refused to join the Confederacy. Johnson would take over as president after Lincoln's death, changing many policies in regards to Reconstruction.
Gideon Welles served in Lincoln's cabinet as Secretary of the Navy. At the time of the Civil War, the Union navy was in shambles. Welles, however, oversaw the construction of improved ironclad ships, instituted key blockades of Confederate ports, and authorized the enlistment of freed slaves into the Navy. In addition, Welles was with Lincoln at the time of his assassination.
Edward Bates was a well-respected lawyer who served in Lincoln's cabinet as Attorney General. Bates lost to Lincoln in the 1860 presidential election, but as Attorney General, supported Lincoln's executive initiatives. In addition to this, Bates was anti-slavery, but did oppose full rights for African Americans, and was also against their serving in the armed services.