Question: When was the president on the back of the bicentennial quarter appointed general of the military branch that John Nixon was affiliated?

full_context: Document 1: American Revolution: In sharp contrast, Congress and the American states had no end of difficulty financing the war. In 1775, there was at most 12 million dollars in gold in the colonies, not nearly enough to cover current transactions, let alone finance a major war. The British made the situation much worse by imposing a tight blockade on every American port, which cut off almost all imports and exports. One partial solution was to rely on volunteer support from militiamen and donations from patriotic citizens. Another was to delay actual payments, pay soldiers and suppliers in depreciated currency, and promise that it would be made good after the war. Indeed, the soldiers and officers were given land grants in 1783 to cover the wages that they had earned but had not been paid during the war. Not until 1781 did the national government have a strong leader in financial matters, when Robert Morris was named Superintendent of Finance of the United States.
Document 2: Kennedy half dollar: In 1971, when silver was eliminated entirely from the coins and production increased, the series began to see improved, but still limited circulation. A special design for the reverse of the half dollar was issued for the United States Bicentennial and was struck in 1975 and 1976. In addition to business strikes, special collector coins were struck for the Bicentennial in silver clad; silver proof sets in which the dime, quarter and half dollar were struck in 90% silver were first minted in 1992. In 2014 a special edition of the Kennedy half dollar was also struck in 99.99% gold.
Document 3: John Knox (British Army officer): John Knox (died 8 February 1778) was an officer in the British Army who took part in the Austrian War of Succession and the Seven Years' War. He served in North America between 1757 and 1760 and is notable for providing historians with the most complete account of these campaigns. Knox narrowly avoided being killed in 1759 when a French soldier's musket twice misfired, and he went on to fight in the Battle of the Plains of Abraham, where he performed in one of the most devastating volleys in military history. Knox also took part in the Battle of Sainte Foy and was present when Montreal surrendered on the 8 September 1760.
Document 4: Commander-in-chief: The amount of military detail handled personally by the President in wartime has varied dramatically. George Washington, the first U.S. president, firmly established military subordination under civilian authority. In 1794, Washington used his constitutional powers to assemble 12,000 militia to quell the Whiskey Rebellion -- a conflict in western Pennsylvania involving armed farmers and distillers who refused to pay excise tax on spirits. According to historian Joseph Ellis, this was the ``first and only time a sitting American president led troops in the field '', though James Madison briefly took control of artillery units in defense of Washington D.C. during the War of 1812.
Document 5: United States Bicentennial coinage: The United States Bicentennial coinage was a set of circulating commemorative coins, consisting of a quarter, half dollar and dollar struck by the United States Mint in 1975 and 1976. Regardless of when struck, each coin bears the double date 1776 -- 1976 on the normal obverses for the Washington quarter, Kennedy half dollar and Eisenhower dollar. No coins dated 1975 of any of the three denominations were minted.
Document 6: Thirteen Colonies: By spring 1775, all royal officials had been expelled, and the Continental Congress hosted a convention of delegates for the 13 colonies. It raised an army to fight the British and named George Washington its commander, made treaties, declared independence, and recommended that the colonies write constitutions and become states. The Second Continental Congress assembled in May 1775 and began to coordinate armed resistance against Britain. It established a government that recruited soldiers and printed its own money. General Washington took command of the Patriot soldiers in New England and forced the British to withdraw from Boston. In 1776, the Thirteen Colonies declared their independence from Britain. With the help of France and Spain, they defeated the British in the American Revolutionary War. In the Treaty of Paris (1783), Britain officially recognized the independence of the United States of America.
Document 7: John Nixon (military): John Nixon (March 1, 1727 – March 24, 1815) was an American brigadier general in the Continental Army during the American Revolutionary War.
Document 8: United States dollar: In February 2007, the U.S. Mint, under the Presidential $1 Coin Act of 2005, introduced a new $1 U.S. Presidential dollar coin. Based on the success of the "50 State Quarters" series, the new coin features a sequence of presidents in order of their inaugurations, starting with George Washington, on the obverse side. The reverse side features the Statue of Liberty. To allow for larger, more detailed portraits, the traditional inscriptions of "E Pluribus Unum", "In God We Trust", the year of minting or issuance, and the mint mark will be inscribed on the edge of the coin instead of the face. This feature, similar to the edge inscriptions seen on the British £1 coin, is not usually associated with U.S. coin designs. The inscription "Liberty" has been eliminated, with the Statue of Liberty serving as a sufficient replacement. In addition, due to the nature of U.S. coins, this will be the first time there will be circulating U.S. coins of different denominations with the same president featured on the obverse (heads) side (Lincoln/penny, Jefferson/nickel, Franklin D. Roosevelt/dime, Washington/quarter, Kennedy/half dollar, and Eisenhower/dollar). Another unusual fact about the new $1 coin is Grover Cleveland will have two coins with his portrait issued due to the fact he was the only U.S. President to be elected to two non-consecutive terms.
Document 9: Half dollar (United States coin): On December 1, 1794, the first half dollars, approximately 5,300 pieces, were delivered. Another 18,000 were produced in January 1795 using dies of 1794, to save the expense of making new ones. Another 30,000 pieces were struck by the end of 1801. The coin had the Heraldic Eagle, based on the Great Seal of the United States on the reverse. 150,000 were minted in 1804 but struck with dies from 1803, so no 1804 specimens exist.
Document 10: Continental Army: The Continental Army was formed by the Second Continental Congress after the outbreak of the American Revolutionary War by the colonies that became the United States of America. Established by a resolution of the Congress on June 14, 1775, it was created to coordinate the military efforts of the Thirteen Colonies in their revolt against the rule of Great Britain. The Continental Army was supplemented by local militias and volunteer troops that remained under control of the individual states or were otherwise independent. General George Washington was the commander - in - chief of the army throughout the war.
Document 11: United States Mint coin sets: All releases from 1936 to 1972 included the cent, nickel, dime, quarter, and half dollar from that year. The first proof sets through 1964 were minted at the Philadelphia Mint. There were two official releases in 1942: one regular five coin set and a set including a silver wartime nickel. United States currency was debased beginning in 1965, but the sets continued under the name United States Mint Proof Set. Production was moved to the San Francisco branch in 1968, and all subsequent issues bear coins with an ``S ''mint mark. In 1973, the Eisenhower dollar was added to the collection. Sets from 1975 will have a dual - date 1776 - 1976 quarter, half - dollar, and dollar as none of those coins were ever produced with a 1975 date. The Susan B. Anthony dollar replaced the Eisenhower in 1979. The 1981 mint sets were the only method of obtaining a Susan B. from that year, though many have slipped into circulation. With the cease in minting of dollar coins, the regular issue Proof Set for 1982 included a brass token. From 1983 until 1998, the annual United States Proof set resumed to only issuing the penny, nickel, dime, quarter, and half - dollar.
Document 12: Continental Army: On June 15, 1775, the Congress elected by unanimous vote George Washington as Commander - in - Chief, who accepted and served throughout the war without any compensation except for reimbursement of expenses.
Document 13: Jethro Sumner: Sumner was named the commanding officer of the 3rd North Carolina Regiment of the North Carolina Line, a formation of the Continental Army, in 1776, and served in both the Southern theater and Philadelphia campaign. He was one of five brigadier generals from North Carolina in the Continental Army, in which capacity he served between 1779 and 1783. He served with distinction in the battles of Stono Ferry and Eutaw Springs, but recurring bouts of poor health often forced him to play an administrative role, or to convalesce in North Carolina. Following a drastic reduction in the number of North Carolinians serving with the Continental Army, Sumner became a general in the state's militia but resigned in protest after the North Carolina Board of War awarded overall command of the militia to William Smallwood, a Continental Army general from Maryland. After the end of the war in 1783, Sumner helped to establish the North Carolina Chapter of the Society of the Cincinnati, and became its first president. He died in 1785 with extensive landholdings and 35 slaves.
Document 14: William Maxwell (Continental Army general): William Maxwell (1733 – November 4, 1796) was an Ulster-born brigadier general in the Continental Army during the American Revolutionary War.
Document 15: John Stark: John Stark (August 28, 1728 – May 8, 1822) was a New Hampshire native who served as an officer in the British Army during the French and Indian war and a major general in the Continental Army during the American Revolution. He became widely known as the "Hero of Bennington" for his exemplary service at the Battle of Bennington in 1777.
ground_truth: June 15, 1775
sub_queries: who is on the back of the bicentennial quarter Answer: Washington
John Nixon >> military branch Answer: Continental Army
when was Washington appointed general of #2 Answer: June 15, 1775