The correct answer is: the participation of the French Armed Forces.
The Battle or Siege of Yorktown took place in 1781, during the American Revolutionary War. It was a victory won by the revolutionary Americans leaded by George Washington who counted with the assistance of the French armed forces leaded by Comte de Rochambeau, over the British who were under the command of General Cornwallis. This victory was important as it enhanced the morale of both the Americans and the French.
Significant changes enacted at the national levels included the imposition of an income tax with the Sixteenth Amendment, direct election of Senators with the Seventeenth Amendment, Prohibition with the Eighteenth Amendment, election reforms to stop corruption and fraud, and women's suffrage through the Nineteenth century
Hope this helps!!
Rivalry
Colonial and imperialistic ambitions was a major contributor of rivalry and hostility that beheld western Europe in the decades before ww1. Each of the nations was seeking to out do each in strategic colonies such as Egypt, east africa,India and some provinces in Europe such as Alasce and Lorraine.
Britain entered World War I in 1914 to honor a treaty that promised to defend Belgium and to fulfill an alliance with France and Russia. The Germans attacked Liege, Belgium, in the first battle of World War I, and then marched on to attack France.
I'm assuming by "war" you mean World War I
