A model of the U.S. Capitol on a huge map of the city during a rehearsal of concept for the upcoming inauguration. (Bill O'Leary/The Washington Post)

Despite an unconventional president-elect known for his lavish taste, military officials responsible for planning his inauguration said Wednesday that the Jan. 20 ceremonies will be steeped in tradition.

The military — which has played an integral role in the event since the country’s first presidential inauguration in 1789 — said it started planning long before Donald Trump was elected. And when dealing with the current president, the president-elect, upward of 800,000 spectators and an expected larger-than-usual number of protesters, there is only so much room for personal flair.

“Generally speaking, inauguration is taking [place] as it has been in the past, though subject to change,” said Brig. Gen. George M. Degnon, a deputy commanding general for the 2017 presidential inauguration. “There’s only so many ways you can make things happen.”

The Joint Task Force National Capital Region — the group responsible for coordinating all military support for the inauguration and many of the logistics for the parade — held what is called a rehearsal of concept Wednesday morning at the D.C. Armory, where it presented a rough outline of what Trump’s Inauguration Day will look like. The task force works alongside the Presidential Inaugural Committee, a private entity, and the Joint Congressional Committee on Inaugural Ceremonies to plan the day.

Officials with the inaugural committee on Wednesday announced that Jackie Evancho, a 16-year-old former “America’s Got Talent” contestant, is set to perform the national anthem. The committee is planning a welcome rally, two official inaugural balls and a ball for military families, veterans and first responders. The theme of the inauguration, according to the committee, will be “Make America great again!”

From left are Brig. Gen. William J. Walker, Maj. Gen. Errol R. Schwartz, Maj. Gen. Bradley A. Becker, and Brig. Gen. George M. Degnon. (Bill O'Leary/The Washington Post)

“This will be a powerfully uniting moment for the American people,” committee Chairman Thomas J. Barrack Jr. said in a statement.

The hallmark of the military rehearsal events is a 60-foot-by-40-foot map of Washington, where officials roughly sketch out the parade route, how military personnel and horses enter the city, where those working the event will meet, and more. There are 3-D models on the map of landmarks, including the White House, Washington Monument and U.S. Capitol. This year, a new building got the model treatment on the map: Trump International Hotel on Pennsylvania Avenue NW.

Assuming Trump decides to stick with tradition, he and Vice President-elect Mike Pence and their spouses will attend church services at St. John’s Episcopal Church near the White House the morning of Jan. 20. They will then go to the White House to sign administrative papers, according to the Army’s Aaron Lovely. From there, they will drive with a motorcade escort to the U.S. Capitol for the swearing-in ceremony around noon, followed by lunch. The newly sworn-in president will then go back to the White House and sit in a viewing stand to watch the parade, which will last about three hours.

“This is mostly based on historical precedence,” Lovely said.

The parade will begin at Pennsylvania Avenue NW, heading west toward the White House. It is unknown what time the parade will start. It has also not yet been decided whether Trump and incoming first lady Melania Trump will leave the presidential vehicle to walk portions of the parade route before they arrive at the White House viewing stand. President Obama walked portions of the route in 2009 and 2013.

“The only thing we know is that there is a swearing-in ceremony at 11:59. Everything else is fluid,” said Navy Reserve Lt. Cmdr. Marvin Terrell Ringer, who is in charge of special events for the inauguration.

Around 13,000 members of the military from around the country will be working in Washington on Inauguration Day, including 5,000 active service members and 8,000 members of the National Guard. They will help with crowd control, escort the ­president-elect, participate in the parade and salute the new president as he passes by. Secret Service officers, D.C. police and Capitol police will also be there for security.

Maj. Gen. Bradley A. Becker, commander of the joint task force, said they do not expect problems with safety, though the military is prepared in the event that anything goes wrong. If needed, officers said, military members outside D.C. will have the capability to quickly move into the nation’s capital.

In the wake of a bitter election, organizers also are gearing up for what is expected to be a large number of protesters. About 20 groups have applied for permits to demonstrate, compared with a handful in past years, according to the National Park Service, which handles permitting.

As in the past, there will be roped-off areas along the parade route for protesters, Becker said.

“The biggest concern right now is the number of potential protesters and how that will impact inauguration, particularly the parade,” he said, adding that potentially freezing weather is also a concern.

Becker said that this will not be a political event for military members.

“We’re trying to instill in them the historical significance of the military support of the peaceful transfer of power,” he said.

Dana Hedgpeth contributed to this report.