Question: What is the county for the birthplace of George Milligan?

full_context: Document 1: John J. Milligan: John Jones Milligan (December 10, 1795 – April 20, 1875) was an American lawyer and politician from Wilmington, in New Castle County, Delaware. He was a member of the Whig Party, who served as United States Representative from Delaware.
Document 2: Archie H. Miller: Miller was born in Hopkins, Minnesota. He served as a state senator from 1931 to 1943, and became Lieutenant Governor after Edward John Thye resigned to become Governor. He served from May 6, 1943 to January 2, 1945.
Document 3: Colo, Iowa: Colo is a city in Story County, Iowa, United States. The population was 876 at the 2010 census. It is part of the Ames, Iowa Metropolitan Statistical Area, which is a part of the larger Ames-Boone, Iowa Combined Statistical Area.
Document 4: Middletown, Iowa: Middletown is a city in Des Moines County, Iowa, United States. The population was 318 at the 2010 census. It is part of the Burlington, IA–IL Micropolitan Statistical Area.
Document 5: George Kinley: George R. Kinley (born June 4, 1937) was an American politician in the state of Iowa and a business co-founder and owner.
Document 6: Indianola, Iowa: Indianola is a city in Warren County, Iowa, United States, 18 miles south of Des Moines, Iowa. The population was 14,782 at the 2010 census. It is the county seat of Warren County.
Document 7: George Milligan (politician): Milligan was born in Des Moines, Iowa. He attended the Washington and Lee University and is a banker. He served in the Iowa State Senate from 1971 to 1975, and House of Representatives from 1969 to 1971 as a Republican. He died in Naples, Florida in 1990 from a heart ailment.
Document 8: Des Moines metropolitan area: The Des Moines metropolitan area, officially known as the Des Moines -- West Des Moines, IA Metropolitan Statistical Area (MSA), consists of five counties in central Iowa, United States: Polk, Dallas, Warren, Madison, and Guthrie. The 2010 census population of these counties was 569,633, and the 2017 estimated population was 645,911.
Document 9: Saylorville, Iowa: Saylorville is a census-designated place (CDP) in Polk County, Iowa, United States. The population was 3,301 at the 2010 census. It is part of the Des Moines–West Des Moines Metropolitan Statistical Area. The Saydel Community School District is located in this area. The unincorporated community of Marquisville is in this area.
Document 10: Joe N. Wilson: Joe Nathan Wilson (November 1, 1922 – August 13, 2015) was an American politician in the state of Iowa. Wilson was born in Centerville, Iowa. He attended the University of Washington Law School and is a farmer. He also served in World War II in the United States Navy. He was a Republican State Senator from Appanoose County from 1961 to 1965. Wilson died in August 2015 at the age of 92. He was interred in Unionville Cemetery in Unionville, Appanoose County, Iowa.
Document 11: Joshua Hill (politician): Following the end of the Civil War, Hill was elected to the United States Senate from Georgia as a Republican in 1867. However, he did not serve in the Senate until 1871 when Georgia was readmitted to the United States. He served in the Senate until the end of his term in 1873 and did not run for reelection. He resumed the practice of law and died in Madison, Georgia.
Document 12: Fort Dodge, Iowa: Fort Dodge is a city in and the county seat of Webster County, Iowa, United States, along the Des Moines River. The population was 25,206 in the 2010 census, an increase from 25,136 in the 2000 census. Fort Dodge is a major commercial center for North Central and Northwest Iowa. It is located on U.S. Routes 20 and 169.
Document 13: Corydon, Iowa: Corydon is a city in Wayne County, Iowa, United States. The population was 1,585 in the 2010 census, a decline from 1,591 in the 2000 census. It is the county seat of Wayne County.
Document 14: William McLean (Ohio politician): William McLean returned to Cincinnati where he engaged in mercantile pursuits and the practice of law. He was also interested in agricultural pursuits. When his health began to fail, he retired from business and spent several months in Cuba hoping to derive benefit for his pulmonary disease by a change of climate. His condition did not improve, and after returning to Cincinnati, he spent some time in revisiting several points in his old Congressional district.
Document 15: Kalona, Iowa: Kalona is a city in Washington County, Iowa, United States. It is part of the Iowa City, Iowa Metropolitan Statistical Area. The population was 2,363 at the 2010 census. Kalona is the second largest city in Washington County.
ground_truth: Warren County
sub_queries: George Milligan >> place of birth Answer: Des Moines
Des Moines >> located in the administrative territorial entity Answer: Warren County