This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

Input: Consider Input: With the defeat of Marshal Bazaine's Army of the Rhine at Gravelotte, the French were forced to retire to Metz, where they were besieged by over 150,000 Prussian troops of the First and Second Armies. Napoleon III and MacMahon formed the new French Army of Chalons, to march on to Metz to rescue Bazaine. Napoleon III personally led the army with Marshal MacMahon in attendance. The Army of Chalons marched northeast towards the Belgian border to avoid the Prussians before striking south to link up with Bazaine. The Prussians, under the command of Field Marshal Count Helmuth von Moltke, took advantage of this maneuver to catch the French in a pincer grip. He left the Prussian First and Second Armies besieging Metz, except three corps detached to form the Army of the Meuse under the Crown Prince of Saxony. With this army and the Prussian Third Army, Moltke marched northward and caught up with the French at Beaumont on 30 August. After a sharp fight in which they lost 5,000 men and 40 cannons, the French withdrew toward Sedan. Having reformed in the town, the Army of Chalons was immediately isolated by the converging Prussian armies. Napoleon III ordered the army to break out of the encirclement immediately. With MacMahon wounded on the previous day, General Auguste Ducrot took command of the French troops in the field.

Output: What factor forced the French to retreat to Metz?

Input: Consider Input: The Compact of Free Association with the United States gives the U.S. sole responsibility for international defense of the Marshall Islands. It allows islanders to live and work in the United States and establishes economic and technical aid programs.

Output: What document governs the defense of the Marshall Islands?

Input: Consider Input: Founded in 1670 as Charles Town in honor of King Charles II of England, Charleston adopted its present name in 1783. It moved to its present location on Oyster Point in 1680 from a location on the west bank of the Ashley River known as Albemarle Point. By 1690, Charles Town was the fifth-largest city in North America, and it remained among the 10 largest cities in the United States through the 1840 census. With a 2010 census population of 120,083 (and a 2014 estimate of 130,113), current trends put Charleston as the fastest-growing municipality in South Carolina. The population of the Charleston metropolitan area, comprising Berkeley, Charleston, and Dorchester Counties, was counted by the 2014 estimate at 727,689 the third-largest in the state and the 78th-largest metropolitan statistical area in the United States.
Output: What year was Charleston founded?