WASHINGTON -- Once the reality of the assault on the U.S. Capitol became apparent, National Guard troops responded appropriately and with alacrity, DOD officials said in a phone briefing today."Yesterday was a horrible and shameful day here in the capital, and the nation at large," Army Secretary Ryan McCarthy said on the call. "The District of Columbia asked the Army for help, and our National Guard responded."McCarthy, Pentagon spokesman Jonathan Rath Hoffman and Kenneth P. Rapuano, the assistant secretary of defense for homeland defense, put the timeline of the National Guard response in perspective during the call.D.C. officials knew of the planned protests and had requested some assistance to help when the "first amendment demonstrations" were planned for January 5 and 6, McCarthy said. Based on this request, officials called up 340 National Guardsmen to help in the peaceful protests. The guardsmen were assigned mainly to traffic control, Metro crowd control, some logistics support and a 40-member quick reaction force to be based at Joint Base Andrews in Maryland."No other requests were made," the Army secretary said.But the peaceful protests turned into a mob rioting through the halls, chambers and offices of the U.S. Capitol. At around 2 p.m., requests came from D.C. Mayor Muriel Bowser for more assistance. Acting Defense Secretary Chris Miller immediately called up 1,100 members of the D.C. National Guard.At the same time, officials were collecting guardsmen at traffic points and Metro stations and returning them to the D.C. Armory to refit for a crowd control mission, the secretary said. They were tasked to support D.C. Metropolitan Police and Capitol Hill Police.Guardsmen started flowing into the area of the Capitol soon after and reinforced Metro Police on the perimeter of the Capitol. This allowed the police and FBI personnel to clear the chambers and offices of the U.S. Capitol, McCarthy said. "By 7:15, both chambers and leadership offices were cleared, and members were able to return to business, and we began the planning for the following day," he said.At 6 p.m., acting Defense Secretary Miller authorized the mobilization of up to 6,200 National Guardsmen from Maryland, Virginia, New York, New Jersey, Delaware and Pennsylvania. These service members will flow into the city over the next few days and will help secure the peaceful transfer of power to President-elect Joseph Biden on January 20."Yesterday's violence at the Capitol was reprehensible and contrary to the tenets of the United States Constitution," Miller said in a written release from the Pentagon. "In the midst of this tragedy, I was proud of the professionalism of our Department of Defense personnel. I want to specifically recognize the service of the District of Columbia National Guard. They performed with honor, integrity and alacrity to protect people and property from unlawful acts."The DOD is in support of the Justice Department, which is the lead federal agency in this situation. They relied on estimates of the Metropolitan Police and Capitol Hill Police. Those organizations, which had experience with pro-Trump groups in November and December, believed the request they made for personnel was adequate. "We don't do domestic [intelligence] collection," Pentagon spokesman Hoffman said. "We rely on Capitol Police and federal law enforcement to provide an assessment of the situation. And based on that assessment that they had, they believed they had sufficient personnel and did not make a request."Estimates of the crowd size were all over the map, Rapuano said.Today, there are 741 National Guardsmen on the Capitol grounds. Guardsmen are also manning traffic checkpoints. They have also put up a non-scalable fence around the Capitol grounds. More guardsmen will arrive in the days ahead."Our Republic may have been disrupted yesterday, but the resolve of our legislators to conduct the people's business did not waver," Miller wrote. "Due to their efforts, supported by local and federal law enforcement and the National Guard, the attempts of those who tried to stop our government from functioning failed. I strongly condemn these acts of violence against our democracy. I, and the people I lead in the Department of Defense, continue to perform our duties in accordance with our oath of office, and will execute the time-honored peaceful transition of power to President-elect Biden on January 20."Related LinksArmy.mil: Worldwide NewsArmy.mil: National Guard NewsDefense.gov