No, it certainly was not a violation of Posse Comitatus. On the contrary, the Federal Government had an affirmative obligation to use Federal troops to restore and maintain domestic peace when confronted by domestic violence used to intimidate the elected representatives of the Federal and local government. The civil government requested the support of Federal troops to quell lethal domestic violence that had already occurred, was threatened to occur, and defend against threats being made against the members of Congress and the Federal Administration. Although it has remained debatable about the extent to which the Communist Party was able to incite domestic violence, it is a fact the Communists were present and were participating in efforts to incite rebellion and domestic violence just as they had already done so in other nations among their veterans.
Constitution of the United States of America. Article. IV. Section. 4. The United States shall guarantee to every State in this Union a Republican Form of Government, and shall protect each of them against Invasion; and on Application of the Legislature, or of the Executive (when the Legislature cannot be convened), against domestic Violence.
The ‘Bonus Army’ War in Washington
Originally published by American History magazine. Published Online: June 12, 2006
http://www.historynet.com/the-bonus-army-war-in-washington.htm
This is DC in 1971 when they arrested 13,000 Americans.
“While protesters listened to music, planned their actions or slept, the authorities quickly moved in 10,000 Federal troops to various locations in the D.C. area, including 4,000 paratroopers from the U.S. 82nd Airborne Division.
At one point, so many soldiers and marines were being moved into the area from bases along the East Coast, that troop transports were landing at the rate of one every three minutes at Andrews Air Force Base in suburban Maryland, about 15 miles from the White House.
These troops were to back up the 5,100 D.C. Metroplitan Police and 2,000 D.C. National Guard troops that were already on the streets.”