A steamship, under the ownership of Lake Erie Transportation Co. (D), was moored at Vincent's (P) dock in order to discharge cargo. A violent storm suddenly swept the area with winds up to 50 m.p.h. The storm was so severe that no master would have been justified in navigating his vessel. The lines to the ship were kept fast to the dock during the ordeal. This resulted in $500 in damages to the dock from the ship being thrown into the dock over and over again the by severe winds. P sued for these damages and the jury gave the verdict to P. D appealed under the defense of necessity.