Perhaps the most influential of President Buchanan's official advisers, he denied the constitutionality of secession, and urged that Fort Sumter be properly reinforced and defended.
He disapproved of Major Anderson's removal of his troops from Fort Moultrie to Fort Sumter in December 1860; but there is probably no basis for the charge made by Southern writers that the removal itself was in violation of a pledge given by the president to preserve the status quo in Charleston harbour until the arrival of the South Carolina commissioners in Washington.
The Civil War between the northern and southern sections of the United States, which began with the bombardment of Fort Sumter on the 12th of April 1861, and came to an end, in the last days of April 1865, with the surrender of the Confederates, was in its scope one of the greatest struggles known to history.
At the close of the first day's bombardment of Fort Sumter (April 12th, 1861) Leroy P. Walker (1817-1884), the Confederate Secretary of War, boasted that before the 1st of May the Confederate flag would float over the Capitol.
In informal conferences with commissioners from the seceded states he assured them that Fort Sumter should be speedily evacuated.
After the fall of Fort Sumter he advocated the enlistment of 500,000 instead of 75, 000 men for a long instead of a short term, and the vigorous enforcement of confiscation measures.