In his declaration of war on April 15, 1861, President Lincoln made an urgent request:
"I appeal to all loyal citizens to favor, facilitate and aid said effort to maintain the honor, the integrity, and the existence of our National Union, and the perpetuity of popular government; and to redress wrongs already long enough endured."
Every member of the Blair family earnestly answered this call to duty.
When President Lincoln filled his Cabinet positions, he appointed Montgomery Blair U.S. Postmaster General. Until his resignation in September 1864, Blair was responsible for ensuring that postal routes remained open in southern post offices still loyal to the Union, as well as facilitating the establishment of free city postal delivery, the adoption of a money order system, and the use of railway mail cars during the Civil War. His placement in the Cabinet was strategic, as Blair was instrumental in keeping Maryland in the Union.
Montgomery Blair, a West Point graduate, had hoped to serve as Secretary of War. Such a title might put him in closer contact with his younger brother, Missouri Congressman Frank Blair Jr., a Union General who actively participated in combat throughout the South, including Sherman's March to the Sea. For his efforts, General U.S. Grant said of Frank Blair, "There was no man braver than he, nor was there any who obeyed all orders of his superior in rank with more unquestioning alacrity."
Throughout his tenure as President, Lincoln relied on Francis P. Blair, Sr. as his "private counselor." In an attempt to bring the rebellion to an end, "Father Blair" went on an authorized mission to Virginia, twice, to secure a peace treaty from Jefferson Davis. The results of these operations were less than successful: "Francis P. Blair, Sr., returned from Richmond, and brought with him precisely what sensible men expected — that is just nothing." In his own words, Blair concurred — calling himself a 'total failure.'
Only a few months after Blair Sr. returned, General Robert E. Lee would surrender in Appomattox and the war would conclude on April 9, 1865. The sweet taste of victory was short-lived as Lincoln was assassinated less than a week later. In her mourning, former First Lady Mary Todd Lincoln sought solace from Elizabeth Blair Lee and her family: "Remember me most truly, to your brother, Judge (Montgomery) Blair, and your dear father & mother & all friends."