Doyle describes the content of the talk as taking off "from my earlier study of US and Italian nationalism to explore a little known but fascinating episode during the Civil War when the Lincoln administration approached Giuseppe Garibaldi to invite him to serve in the Union Army. It set off a wave of rumors in the US and Europe and, so I argue, reveals how the purpose of the war, in North and South, was defined largely in response to European public opinion, not just diplomacy".