Secession or Insurrection?

[Southern Cal]

Having recently studied closely the chronology leading up the the "War between the States", I found that, with the exception of South Carolina, most of the Southern States seized federal property before seceding. Here is a brief timeline:

December 20, 1860: South Carolina convention passes odinance of secession.

December 26, 1860: Major Anderson moves Federal garrison in Charleston to from Fort Moultire to Fort Sumter. South Carolina State Militia takes possession of Fort Moultrie.

January 3, 1861: Georgia seizes Federal Fort Pulaski.

January 4, 1861: Alabama seizes Federal arsenal at Mount Vernon.

January 5, 1861: Alabama seizes Federal Forts Morgan and Gaines.

January 6, 1861: Florida seizes Federal Apalachicola arsenal.

January 7, 1861: Florida seizes Federal Fort Marion.

January 8, 1861: Floridians foiled in attempt to seize Federal Fort Barrancas.

January 9, 1861: Mississippi secedes.

January 9, 1861: "Star of the West" fired on in Charleston Harbor by South Carolina forces.

January 10, 1861: Florida secedes.

January 10, 1861: Louisiana seizes Federal Forts Jackson and St. Philip, and U.S. arsenal at Baton Rouge.

January 11, 1861: Alabama secedes.

January 11, 1861: Louisiana seizes Unites States Marine Hospital.

January 14, 1861: Louisiana seizes Federal Fort Pike.

January 19, 1861: Georgia secedes.

January 26, 1861: Louisiana secedes.

February 1, 1861: Texas secedes

February 8, 1861: Arkansas seizes Federal Arsenal at Little Rock.

February 12, 1861: Arkansas seizes U.S. Ordnance Dept. stores at Napoleon.

February 18, 1861: Jefferson Davis Inaugurated as President of the Confederate States of America.

March 4, 1861: Abraham Lincoln inaugurated as 16th President of the United States.

April 12, 1861: Fort Sumter fired on by Confederate forces.

From the above historical record, one can see that: while still legally and officially part of the United States, while a Democrat President with Southern sympathies occupied the White House, while the U.S. Congress was in session, and while the federal court were operating, the State Militias or bands of armed men sanctioned by the states mentioned above, seized Federal property. These acts violated United States law, since these individual states were still part of the U.S. when these acts occurred, seceding only later. Am I wrong, or do these acts constitute armed insurrection by individual States against the United States? Didn't armed insurrection oblige President Buchanan and later, President Lincoln, to take action as Chief Executive to enforce the law?

Source: The American Civil War Home Page