The term 'Gettysburg Addresser' refers to Abraham Lincoln, the 16th President of the United States. He is best known for delivering the Gettysburg Address in 1863, a speech that is widely considered one of the most important speeches in American history. The speech was delivered at the dedication of the Soldiers' National Cemetery in Gettysburg, Pennsylvania, and it helped to redefine the Civil War as a struggle for freedom and equality.