“After Anderson’s move to Sumter, a dismayed President faced angry commissioners, who sought the surrender of Fort Sumter, a position that several of his cabinet officers supported.
“Secretary of the Interior (Jacob) Thompson noted that South Carolina was a small state with a sparse white population.
“Why not evacuate property that southerners believed they owned under the doctrine of eminent domain?
“They would buy the fort.
“Moreover, Anderson had violated the earlier agreements with South Carolina that the state had made with Buchanan—or at least thought that it had made.” (note: The state of South Carolina adhered to the agreement until Anderson violated it.
James Buchanan by Jean H. Baker, 2004
Buchanan had indeed made the agreement with South Carolinians. Here, in an old post of mine, are some quotes from an unsent letter by Attorney General Edwin Stanton who participated in the cabinet meeting discussions about this with Buchanan that confirm the agreement: http://www.freerepublic.com/focus/news/2484139/posts?page=1222#1222
Stanton's account in the letter was later verified by Joseph Holt who had participated in those cabinet meetings as Buchanan's Postmaster General.
Buchanan faced the resignation of three of his cabinet members (Stanton and two others -- possibly Toucey, Black, Thomas, or Holt) if he stuck with the agreement he had made with South Carolinians and did not back Anderson's move to Sumter. Buchanan had already suffered the loss of two cabinet members (Howell Cobb of Georgia on December 8, 1860 and Lewis Cass of Michigan on December 12 or 13, 1860) and faced the prospect of losing two more from potential scandals (John Floyd and Jacob Thompson). Buchanan finally caved to the pro Union group (Stanton and others) and came out with a public statement that distanced himself from any previous agreement with the South Carolinians.
Anderson's move to Sumter did not play well with South Carolinians. From page 8 of the Jan. 1, 1861, New York Times, reporting an article from the Charleston Courier of Dec. 28, 1860. (Italics as reported in the Times):
The newspaper offices were besieged, the hotel halls were thronged, and even the grave and serious gentlemen composing the State Convention shared in the general excitement. On all hands anger and indignation was expressed at the supposed perfidious conduct of the Federal authorities, at whose instance it was first thought the movement was made. The people were greatly incensed at the idea of a willful breach of those assurances of non action which had been volunteered by the Government at Washington and upon which so much reliance and confidence had been placed by the entire population, that every impulse to take the necessary precautions for their own safety had been restrained.
Instinctively men flew to arms. Orders were immediately issued to the following Companies to hold themselves in readiness for service: Washington Light Infantry, Capt. C. H. Simonton; Carolina Light Infantry, Capt. B. G. Pinckney; Meagher Guards, Capt. Ed. McCready, Jr.; altogether forming a portion of the Regiment of Rifles, commanded by Col. J. J. Pettigrew and Major Ellison Capers; also, to the Marion Artillery, Capt. J. G. King; Lafayette Artillery, Capt. J. J. Pope, Jr.; Washington Artillery, Capt. G. H. Walter; German Artillery, Capt. C. Nohrden; all under command of Lieut. W. G. De Saussure; Adjutant, Jas. Simmons, Jr.; Sergeant-Major, E. Prioleau Ravenel; Quartermaster-Sergeant, J. R. Macbeth; Surveyor, A Barbot: Surgeons, P. Gervais Robinson and Middleton Mitchel. Also, the Palmetto Guard, Capt. Thomas Middleton, and Cadei Riflemen, W. S. Elliot.
All the military forces thus ordered out promptly obeyed the summons, and the streets were soon enlivened by the appearance of individual members of the different organizations in their uniforms.
Anderson really escalated tensions by his move. Another article from that issue of the Times quoted from the Courier as saying:
Maj. Robert Anderson, U. S. A., has achieved the unenviable distinction of opening civil war between American citizens by an act of gross breach of faith.