Germany was already rationing food when the bad harvests of 1916 made the situation far worse. Running out of options, the German military decides to resume unrestricted U-boat warfare.

The European powers refused to negotiate, but private groups, including women's groups, socialists, and Henry Ford, pressed ahead with campaigns to bring the belligerents to the negotiating table.

The automobile and the airplane, both recent inventions that make use of the internal combustion engine, become weapons of war.