Washington's birthday, 1861, just weeks before the start of the Civil War. President-elect Abraham Lincoln took off his hat and coat and raised the first 34-star flag above Independence Hall. Kansas had entered the Union.

Nearby, looking smart in epaulets and crisp gray uniforms, were the Washington Grays, one of Philadelphia's most popular military units. They raised their muskets high and fired a salute.

"As the sun just rising kissed the quivering folds of the national emblem, a cheer arose from thousands of loyal throats that was an earnest expression of the unflinching devotion of the City of Brotherly Love," wrote a member of the Grays.

A simple plaque on the walkway at Independence Hall now commemorates that moment. It's a reminder of a bygone age when Philadelphia was part of a great crusade to save the Union.

In nearly every corner - from City Hall and Laurel Hill Cemetery to Memorial Hall and the Benjamin Franklin Parkway - statues, monuments, buildings, and artifacts speak of the city's role in what some have called the "second revolution."

The 150th anniversaries of events during that pivotal period will be marked in a series of programs, observances, exhibits - and even large battle reenactments in Fairmount Park - through 2015.

The effort will be launched at a fund-raising reception at 6 p.m. Monday at the National Constitution Center, which will host military reenactors, period music, and a preview of the film Civil War Philadelphia.

The city's history during the war "is a story that few people know about; we're not just a one-war town," said John Meko Jr., chair of the Civil War History Consortium of Greater Philadelphia, a nonprofit made up of dozens of Civil War- and history-related groups and institutions involved in the coming events.

Philadelphia "has been called one of the great battlefields of the Civil War - a battlefield of commerce, politics, and national finance," said Kim Sajet, vice chair of the consortium and president and chief executive officer of the Historical Society of Pennsylvania.

"It was also one of the great battlefields in the struggle for freedom and equality for African Americans."

The effort to share this history during the war's sesquicentennial will begin April 16 at the National Constitution Center, across from the spot visited by Lincoln as the incoming president, then revisited to lie in state after the assassination in 1865.

A parade of more than 1,000 uniformed reenactors and present-day soldiers, accompanied by brass bands, will recall the departure of the first Union troops from Philadelphia.

"We're trying to educate the public," said Andy Waskie, a Temple University professor, historian, and author who is a member of the consortium board. "Philadelphia was the arsenal of freedom, manufacturing everything from bayonets and cartridges to cannon, flags, drums, and uniforms.

"It had shipyards, and 24 hospitals, including the two largest in the nation with 4,000 beds each," said Waskie, the parade marshal, who will portray Union Gen. George Gordon Meade, the victorious leader of federal forces at the Battle of Gettysburg.

"It also had 30 camps of different units. Camp William Penn trained African American troops and was located just across Cheltenham Avenue in Montgomery County."

The parade will stop for a review at the Union League of Philadelphia at Broad and Sansom Streets, near a 700-pound bronze statue dedicated to the Washington Grays, who fought in all of the war's major battles.

"Dear Parents," wrote one soldier in 1863, "I will endeavor to give you a faint description of our reception in Philadelphia, but I know my pen cannot half do justice to the subject. . . . Anyone who thinks there is any lack of support for the war had only to march to Philadelphia."

The parade reenactors will head south from the League to the site where soldiers boarded trains at Broad Street and Washington Avenue. There, they will set up camp and demonstrate drilling, weapons firing, and camp life. The day will end with a gala ball at the Union League.

But that's just the start. Union and Confederate armies may never have fought in the city, but at least 1,000 blue- and gray-clad reenactors will stage a major battle reenactment and living-history encampment on Aug. 20 and 21. It will be the first of several at the site over the sesquicentennial.

Dozens of institutions and organizations in the consortium also are planning events, and a guide to Civil War research in Philadelphia-area collections is being produced.

One treat for history buffs will be the opening of the Heritage Center at the Union League, where the public will be invited to see treasures including a signed copy of the Emancipation Proclamation and the original eyewitness testimony taken in Washington as Lincoln lay dying from an assassin's bullet.

The League was formed in 1862 as a patriotic society to support Lincoln and the Union. Now one of the nation's leading private city clubs, it will offer changing public exhibits in its Heritage Center and guided tours of its building.

"We want to bring [the city's Civil War] history to as many people as we can," said Meko, who is also executive director of the Foundations of the Union League, a nonprofit providing scholarships, supporting education, and caring for the club's collections.

Many other organizations also have plans:

The Historical Society of Pennsylvania Digital Center for Americana has processed 52 Civil War-related collections for research. More than 9,000 images from these collections will soon be available online.

The College of Physicians/Mutter Museum will mark the Civil War's and its own 150th anniversary in 2013 with an exhibit on the medical treatment and mortality during the period.

The African American Museum in Philadelphia has a permanent ongoing exhibition called "Audacious Freedom," chronicling the city's black leaders through the nation's Centennial.

The Rosenbach Museum and Library will have several offerings, including an online project, "Today in the Civil War," with examples drawn from its collections, and an exhibition on the beginning of the Civil War from Dec. 15 to July 17.

Philadelphia gives people "two revolutions for the price of one," said Laura Blanchard, executive director of the consortium. "The Civil War was about the soldier and conflict, but it was also about how diverse population groups came together in support of the Union and challenged the status quo in pursuit of their own freedom and equality.

"We think it's important for them to understand the rich heritage we have."