As he stepped down from the podium at the Gettysburg battlefield in 1863, President Abraham Lincoln was unhappy. The speech was short and finished abruptly. The crowd was slow to clap. Lincoln turned to friend and occasional bodyguard Ward Lamon. ‘That speech won’t scour,’ he told Lamon. ‘It is a flat failure, and the people are disappointed.’

Lincoln placed great value on persuasion through carefully prepared speeches. The Gettysburg Address summed up his key ideas developed over a decade: that America is a unique experiment in human history, a republic based on the equality of individuals, an ideal so important that civil war must be fought and won so that government by, for and of the people should not perish from the earth.