And they thought we wouldn't fight

the long version

"On the night of February 27, 1917, when the Laconia was two hundred miles off the coast of Ireland, the Gibbons' "hunch" was fulfilled. The Laconia was torpedoed and sunk. After a perilous night in a small boat on the open sea, Gibbons was rescued and brought into Queenstown. He opened the cables and flashed to America the most powerful call to arms to the American people. It shook the country. It was the testimony of an eye witness and it convinced the Imperial German government, beyond all reasonable doubt, of the wilful and malicious murder of American citizens. The Gibbons story furnished the proof of the overt act and it was unofficially admitted at Washington that it was the determining factor in sending America into the war one month later" -- Foreword.