On the night of April 14, 1865, he was a witness, at Ford's Theatre, to the assassination of President Lincoln. He wisely presumed that other high officers of the Lincoln administration might also be endangered by the conspiracy and rushed to the Vice President's boarding place, arriving in time to summon additional guards and save Andrew Johnson from the knife of George Atzerodt. Governor Farwell then proceeded to Secretary William H. Seward's residence but arrived too late to prevent that attack. President Johnson later offered Farwell any appointment he wanted in the federal government, but Farwell declined, choosing to continue his work in the Patent Office.