Question: General John J. Pershing operated on which main theatre of war during the First World War?
Context: Mark Matthews (August 7, 1894 – September 6, 2005) was an American veteran of the Second World War and a Buffalo Soldier.  Born in Alabama and growing up in Ohio, Matthews joined the 10th Cavalry Regiment when he was only 15 years old, after having been recruited at a Lexington, Kentucky racetrack and having documents forged so that he appeared to meet the minimum age of 17.  While stationed in Arizona, he joined General John J. Pershing's Mexico expedition to hunt down Mexican general Pancho Villa.  He was later transferred to Virginia, where he took care of President Roosevelt and First Lady Eleanor's horses and was a member of the Buffalo Soldiers' drum and bugle corps.  In his late 40s, he served in combat operations in the South Pacific during World War II and achieved the rank of First Sergeant.  He was noted as an excellent marksman and horse showman. This article is about the United States campaigns in World War I. American entry into World War I in early April 1917 resulted in the American Expeditionary Force (AEF) on the Western Front, under General John J. Pershing, being engaged in 13 campaigns, during the period 1917–18, for which campaign streamers were designated.  The streamer uses the colors of the World War I Victory Medal ribbon which had a red center with a rainbow on each side of the center stripe and a purple edge.  The double rainbow symbolizes the dawn of a new era and the calm which follows the storm. The Village of Columbus and Camp Furlong is a National Historic Landmark District commemorating the 1916 raid by Pancho Villa on the town of Columbus, New Mexico, and the American military response to that raid, the "Punitive Expedition" led by General John J. Pershing.  The raid and its response, set during World War I, the Mexican Revolution, and an accompanying low-level Border War, played a significant role in diplomacy and military preparedness for eventual American entry in the World War.  The district encompasses buildings which survived the raid, and military facilities used in the American response.  The landmark designation was made in 1975. The Great Pershing Balloon Derby is a hot air balloon festival held each Labor Day weekend near Brookfield, Missouri.  The three-day festival draws balloonists from the midwest and as far away as Florida and the Pacific Northwest.  It is named in honor of General John J. Pershing, leader of the American Expeditionary Forces in World War I and a native of nearby Laclede, Missouri.  The Great Pershing Balloon Derby (GPBD) has been recognized as the longest running continually sanctioned ballooning event in the U.S. by the Balloon Federation of America. John J. Pershing General of the Armies, is a public artwork by American artist Robert White, located at Pershing Park in Washington, D.C., United States.  John J. Pershing General of the Armies was originally surveyed as part of the Smithsonian's Save Outdoor Sculpture!  survey in 1994.  The monument is a tribute to United States Army general John J. Pershing. The Western Front was the main theatre of war during the First World War.  Following the outbreak of war in August 1914, the German Army opened the Western Front by invading Luxembourg and Belgium, then gaining military control of important industrial regions in France.  The tide of the advance was dramatically turned with the Battle of the Marne.  Following the Race to the Sea, both sides dug in along a meandering line of fortified trenches, stretching from the North Sea to the Swiss frontier with France, which changed little except during early 1917 and in 1918. Charles Egbert Stanton (November 22, 1858 – May 8, 1933) was an officer in the United States Army, and attained the rank of colonel.  A veteran of the Spanish–American War, and served as chief disbursing officer and aide to General John J. Pershing during World War I.  Stanton was the nephew of Abraham Lincoln's Secretary of War, Edwin M. Stanton.  He is best known for having included the memorable expression "Lafayette, we are here!"  in a speech he gave in Paris during the First World War. John J. Pershing Intermediate School 220, is a public middle school located at 4812 Ninth Avenue in the Sunset Park neighborhood of Brooklyn, New York City.  It was founded in the 1970s, and was named after World War I general John J. Pershing. The General Pershing Zephyr was the ninth of the Chicago, Burlington and Quincy Railroad's "Zephyr" streamliners, and the last built as an integrated streamliner rather than a train hauled by an EMD E-unit diesel locomotive.  It was constructed in 1939 with bodywork and passenger cars by Budd Company and diesel engine, electric transmission, power truck, and other locomotive equipment by General Motors Electro-Motive Corporation.  Because its intended Kansas City, Missouri to St. Louis, Missouri route passed near the birthplace and boyhood home of famous World War I General John J. Pershing, the train was named after him.  The power car was named "Silver Charger", after Pershing's horse "Charger", while the passenger cars were named after U.S. Army badges of rank—"Silver Leaf", "Silver Eagle", and "Silver Star". Major General Ralph Corbett Smith (November 27, 1893 – January 21, 1998) was a senior officer of the United States Army.  After receiving early training as a pilot from Orville Wright he served Brigadier General John J. Pershing's army against Pancho Villa, became decorated for bravery in World War I and commanded the 27th Infantry Division in combat in the Pacific War in World War II.  At his death Smith was the oldest surviving general officer of the Army.
Answer: The Western Front