Task: Question Answering
Input (English): Passage: Ricketts Glen State Park is in the Susquehanna River drainage basin, the earliest recorded inhabitants of which were the Iroquoian-speaking Susquehannocks. Their numbers were greatly reduced by disease and warfare with the Five Nations of the Iroquois, and by 1675 they had died out, moved away, or been assimilated into other tribes. After this, the lands of the Susquehanna valley were under the nominal control of the Iroquois, who encouraged displaced tribes from the east to settle there, including the Shawnee and Lenape (or Delaware).On November 5, 1768, the British acquired land, known in Pennsylvania as the New Purchase, from the Iroquois in the Treaty of Fort Stanwix; this included what is now Ricketts Glen State Park. After the American Revolutionary War, Native Americans almost entirely left Pennsylvania. Luzerne County was formed in 1786 from part of Northumberland County, and Fairmount Township, where the waterfalls are, was settled in 1792 and incorporated in 1834. About 1890 a Native American pot, decorated in the style of "the peoples of the Susquehanna region", was found under a rock ledge on Kitchen Creek by Murray Reynolds, for whom a waterfall is named.The Ricketts family began acquiring land in and around what became the park in 1851, when Elijah Ricketts and his brother Clemuel bought about 5,000 acres (2,000 ha) on North Mountain around what is now known as Ganoga Lake. By 1852 they had built a stone house on the lake shore, which they ran "as a lodge and tavern". Elijah's son Robert Bruce Ricketts, for whom the park is named, joined the Union Army as a private at the outbreak of the American Civil War and rose through the ranks to become a colonel. After the war, R. B. Ricketts returned to Pennsylvania and began purchasing the land around the lake from his father in 1869; eventually he controlled or owned more than 80,000 acres (32,000 ha), including the glens and waterfalls.Ricketts and the other settlers living in the area were not aware of the glens and their waterfalls until about 1865, when they were discovered by two of the Ricketts' guests who went fishing and wandered down Kitchen Creek. In 1872 Ricketts built a three-story wooden addition to the stone house; this opened as the North Mountain House hotel in 1873, and was run by Ricketts' brother Frank until 1898. 
Question: What year did the Union army private who has a park named after him discover the glens and waterfalls on his property?
Output (English): 1865.