Question: What military branch was served in by the president during the purchase of the state where Tana Glacier is located?

full_context: Document 1: Department of Alaska: The Department of Alaska was the designation for the government of Alaska from its purchase by the United States of America in 1867 until its organization as the District of Alaska in 1884. During the department era, Alaska was variously under the jurisdiction of the U.S. Army (until 1877), the U.S. Dept. of the Treasury (from 1877 until 1879) and the U.S. Navy (from 1879 until 1884). The area later became the District of Alaska, then the Territory of Alaska, then the State of Alaska.
Document 2: John Aaron Rawlins: John Aaron Rawlins (February 13, 1831 September 6, 1869) was a general officer in the Union Army during the American Civil War and a cabinet officer in the Grant administration. A longtime confidant of Ulysses S. Grant, Rawlins served on Grant's staff throughout the war, rising to the rank of brevet major general, and was Grant's chief defender against allegations of insobriety. He was appointed Secretary of War when Grant was elected President of the United States.
Document 3: Yahtse Glacier: Yahtse Glacier is a 40-mile-long (64 km) glacier in the U.S. state of Alaska. It begins on the southeast slope of Mount Miller and trends southeast along the north border of Guyot Glacier to Icy Bay, just east of Guyot Hills and 70 miles (113 km) northwest of Yakutat. The western extent is an icefield. The name derives from the Yahtse River and was adopted after the retreat of Guyot Glacier resulted in a separate branch.
Document 4: Little Susitna River: Little Susitna River heads at Mint Glacier on Montana Peak, in Talkeetna Mountains at , flows southwest to Cook Inlet, west of Anchorage, Alaska Cook Inlet Low.
Document 5: Lincoln (novel): Set during the American Civil War, the novel describes the presidency of Abraham Lincoln through the eyes of several historical figures, including presidential secretary John Hay, First Lady Mary Todd Lincoln, Secretary of State William H. Seward, Secretary of the Treasury Salmon Chase, his daughter Kate Chase, U.S. Representative Elihu B. Washburne, and conspirators John Wilkes Booth and David Herold.
Document 6: Reconstruction era: As Confederate states came back under control of the U.S. Army, President Abraham Lincoln set up reconstructed governments in Tennessee, Arkansas, and Louisiana during the war. He experimented by giving land to blacks in South Carolina. By fall 1865, the new President Andrew Johnson declared the war goals of national unity and the ending of slavery achieved and reconstruction completed. Republicans in Congress, refusing to accept Johnson's lenient terms, rejected new members of Congress, some of whom had been high - ranking Confederate officials a few months before. Johnson broke with the Republicans after vetoing two key bills that supported the Freedmen's Bureau and provided federal civil rights to the freedmen. The 1866 Congressional elections turned on the issue of Reconstruction, producing a sweeping Republican victory in the North, and providing the Radical Republicans with sufficient control of Congress to override Johnson's vetoes and commence their own ``Radical Reconstruction ''in 1867. That same year, Congress removed civilian governments in the South, and placed the former Confederacy under the rule of the U.S. Army. The army conducted new elections in which the freed slaves could vote, while whites who had held leading positions under the Confederacy were temporarily denied the vote and were not permitted to run for office.
Document 7: Alaska Purchase: The Alaska Purchase (Russian: Продажа Аляски, tr. Prodazha Alyaski) was the United States' acquisition of Alaska from the Russian Empire on March 30, 1867, by a treaty ratified by the United States Senate, and signed by president Andrew Johnson.
Document 8: Catharinus P. Buckingham: Catharinus Putnam Buckingham (March 14, 1808 – August 30, 1888) was an American soldier, college professor, author, and industrialist. He served as a general in the Union Army during the American Civil War, and was the main assistant to the U.S. Secretary of War, Edwin M. Stanton, during part of the first term of the Lincoln Administration.
Document 9: Glacier View, Alaska: Glacier View is a census-designated place (CDP) in Matanuska-Susitna Borough, Alaska, United States. It is part of the Anchorage, Alaska Metropolitan Statistical Area. At the 2010 census the population was 234, down from 249 in 2000. The terminus of Matanuska Glacier is located approximately three miles southwest of Glacier View.
Document 10: Lafayette C. Baker: Lafayette Curry Baker (October 13, 1826 – July 3, 1868) was a United States investigator and spy, serving the Union Army, during the American Civil War and under Presidents Abraham Lincoln and Andrew Johnson.
Document 11: Alaska Purchase: The Alaska Purchase (Russian: Продажа Аляски, tr. Prodazha Alyaski) was the United States' acquisition of Alaska from the Russian Empire on March 30, 1867, by a treaty ratified by the United States Senate, and signed by President Andrew Johnson.
Document 12: Alaska Purchase: Russia continued to see an opportunity to weaken British power by causing British Columbia, including the Royal Navy base at Esquimalt, to be surrounded or annexed by American territory. Following the Union victory in the Civil War, the Tsar instructed the Russian minister to the United States, Eduard de Stoeckl, to re-enter into negotiations with William H. Seward in the beginning of March 1867. President Johnson was entangled in negotiations about Reconstruction and Seward had alienated a number of Republicans, so they believed that the purchase would help divert attention from the domestic issues. The negotiations concluded after an all - night session with the signing of the treaty at 04: 00 on March 30, 1867, with the purchase price set at $7.2 million ($105 million in 2016), or about 2 cents per acre ($4.74 / km).
Document 13: Alaska Purchase: Russia continued to see an opportunity to weaken British power by causing British Columbia, including the Royal Navy base at Esquimalt, to be surrounded or annexed by American territory. Following the Union victory in the civil war, the Tsar instructed the Russian minister to the United States, Eduard de Stoeckl, to re-enter into negotiations with William Seward in the beginning of March 1867. President Johnson was entangled in negotiations about Reconstruction and Seward had alienated a number of Republicans, so they believed that the purchase would help divert attention from the current domestic matters. The negotiations concluded after an all - night session with the signing of the treaty at 04: 00 on March 30, 1867, with the purchase price set at $7.2 million ($123 million today), or about 2 cents per acre ($4.74 / km).
Document 14: Alatna River: The river is very popular for float trips due to its calm flow and wonderful scenery. Float trips usually take from four to fourteen days, depending on put-in spot and pick-up spot, and also weather/river conditions. One common place to put in is Circle Lake, a small lake which is float plane accessible and is located in a beautiful part of the valley. Another place to put in is Takahula Lake, a larger, float-plane accessible lake, further downstream from Circle Lake. Gaedeke Lake is also a possible put in spot, but according to the "Alaska River Guide", this upstream section near the headwaters of the river is shallow and rocky making portaging or lining necessary. Most floaters take out at the village of Allakaket.
Document 15: Tana Glacier: Tana Glacier is a 17-mile-long (27 km) glacier in the U.S. state of Alaska. It begins at Bagley Icefield and flows northwest to its 1950 terminus near the head of the Tana River. Its name, of Alaska Native origin, was first recorded by prospectors in 1900.
ground_truth: Union Army
sub_queries: What state is Tana Glacier located? Answer: Alaska
who was the president when Alaska was purchased Answer: Andrew Johnson
Andrew Johnson >> military branch Answer: Union Army