The Army on Wednesday started loading up some of the tanks that will take to the streets of the nation's capital during the 250th anniversary celebration of the service next month, which will feature hundreds of military vehicles and aircraft and thousands of soldiers.

The event has grown extensively in scope and size since Army planners started working on a festival two years ago to mark the day and have now added a military parade — which President Donald Trump had unsuccessfully tried to do during his first term.

The Army's anniversary celebration is set for June 14, which also happens to be Trump’s birthday.

It will include concerts, fireworks, NFL players, fitness competitions and displays all over the National Mall for daylong festivities. The Army expects as many as 200,000 people could attend and that putting on the celebration will cost an estimated $25 million to $45 million.

Here's what to expect during the all-day festival and 6 p.m. parade:

The tanks and armored vehicles

The Army was putting 28 M1 Abrams main battle tanks onto rail cars at Fort Cavazos in Texas on Wednesday. The tanks weigh more than 60 tons apiece and will take about nine or 10 days to travel by rail to Maryland, where they will be loaded onto trucks to be driven into Washington, D.C. and offloaded at a staging area near the Lincoln Memorial.

On the day of the parade, those tanks as well as 28 tracked Bradley Fighting Vehicles, 28 wheeled Stryker combat vehicles, four tracked M-109 Paladin self-propelled howitzers and other towed artillery will maneuver to the start of the parade route just off the National Mall. They will travel toward the White House, driving over thick metal plating to protect the streets at some parade points where the vehicles make a sharp turn.

The Army said it's also planning some additional asphalt work and putting new rubber padding on the tanks' metal tracks to try to minimize street damage.

The influx of soldiers

More than 6,700 soldiers will travel from bases around the country to participate in the parade and festival and spend June 11-15 housed in two nearby federal buildings, sleeping on cots and having packaged military meals ready-to-eat, or MREs, for breakfast and lunch.

They will get a hot meal for dinner and a $69 per diem to buy additional food as they want, Army spokesman Steve Warren said.

They will be forming units that represent each of the nation's major conflicts, starting with the Revolutionary War. For each conflict, 60 soldiers will wear period uniforms supplied by an event company representing that war and be followed by 400 soldiers from their same base in present-day uniforms.

Not all of the soldiers participating will be in the parade — or even on the ground. For instance, Col. Anne McClain, an Army astronaut currently serving on the International Space Station, will participate.

At the end of the parade, the Army's Golden Knights parachute team will jump over the White House, landing near Trump to present him with a folded flag, and 250 new recruits or reenlisting service members will be sworn in to the Army by Trump.

The aircraft and helicopters buzzing overhead

More than 50 helicopters and aircraft representing different wars will fly over the city — pairing up with the units on the ground as they pass the president.

For example, as units marching in World War II uniforms pass Trump, a P-51 Mustang fighter aircraft and a B-25 Mitchell bomber aircraft are expected to fly overhead.

As units representing more recent conflicts pass, Army H-1 Huey, AH-1 Cobra, AH-64 Apache and CH-47 Chinook helicopters will appear in the sky.

The helicopters are flying at a time when sharing D.C.'s airspace is still a sensitive issue after a January collision between an Army Black Hawk helicopter and an American Airlines regional jet killed 67.

Warren said the Army has worked closely with the Federal Aviation Administration on routes, and the helicopters will take off from Andrews Air Force Base to fly toward the Capitol.

It's likely D.C.'s airspace may be temporarily closed to airline traffic as the sky parade occurs, the Army said.

Here's what to expect at the Army's 250th anniversary parade on Trump's birthday