The Mercury Orchestra, national winner of the 2010 American Prize in Orchestral Performance, examines snapshots of American history in the 250th anniversary of the Declaration of Independence, through the musical prisms of three mid-20th century American composers. African-American composer and conductor Julia Perry wrote A Short Piece for Large Orchestra, an imperious, kinetic delight. William Schuman’s secular cantata A Free Song (featuring the New World Chorale) declaims the Civil War era poetry of Walt Whitman in a reflective dialogue that expresses a desire for freedom for all mankind; this work awarded the first Pulitzer Prize for Music in 1943. Roy Harris’s stirring sixth symphony vividly brings to life the noble exhortations of Lincoln’s Gettysburg Address, to honor the ideal that all men were created equal.