Question: What Georgia county is Georgia Department of Defense headquartered at?

Context paragraphs:
Georgia National Guard: The Georgia National Guard is the National Guard of the U.S. state of Georgia, and consists of the Georgia Army National Guard and the Georgia Air National Guard.  (The Georgia State Defense Force is the third military unit of the Georgia Department of Defense, part of the Government of Georgia.)  The Constitution of the United States specifically charges the National Guard with dual federal and state missions.  The state functions range from limited actions during non-emergency situations to full scale law enforcement of martial law when local law enforcement officials can no longer maintain civil control.

Geologic map of Georgia (U.S. state): The geologic map of Georgia (a state within the United States) is a special-purpose map made to show geological features.  Rock units or geologic strata are shown by colors or symbols to indicate where they are exposed at the surface.  Structural features such as faults and shear zones are also shown.  Since the first national geological map, in 1809, there have been numerous maps which included the geology of Georgia.  The first Georgia specific geologic map was created in 1825.  The most recent state-produced geologic map of Georgia, by the Georgia Department of Natural Resources is 1:500,000 scale, and was created in 1976 by the department's Georgia Geological Survey.  It was generated from a base map produced by the United States Geological Survey.  The state geologist and Director of the Geological Survey of Georgia was Sam M. Pickering, Jr.  Since 1976, several geological maps of Georgia, featuring the state's five distinct geologic regions, have been produced by the federal government.

Georgia Department of Economic Development: The Georgia Department of Economic Development (GDEcD) is a department of the State of Georgia (United States).  The department plans, manages and mobilizes state resources to attract new business investment to Georgia, drive the expansion of existing industry and small business, locate new markets for Georgia products, inspire tourists to visit Georgia and promote the state as a top destination for arts events and film, music and digital entertainment projects.

Protected areas of Georgia (U.S. state): The protected areas of Georgia cover almost one million acres (4,000 km²) of the state.  These areas are managed by different federal and state level authorities and receive varying levels of protection.  Some areas are managed as wilderness while others are operated with acceptable commercial exploitation.  On the Federal level, Georgia contains 1 Biosphere Reserve, 4 National Parks, 1 National Forest and 8 Wildlife Refuges.  Georgia is home to 63 state parks, 48 of which are state parks and 15 that are National Historic Sites, and many state wildlife preserves, under the supervision of the Georgia Department of Parks and Recreation, a division of the Georgia Department of Natural Resources.

Marietta, Georgia: Marietta is located in central Cobb County, Georgia, United States, and is the county's seat and largest city.

Georgia State Defense Force: The Georgia State Defense Force (GSDF, GASDF, or SDF) is an unpaid, volunteer component of the Georgia Department of Defense, serving in support of the national and state constitutions under direction of the governor and the adjutant general of Georgia.  As a State Defense Force, members serve alongside the Georgia Army National Guard and the Georgia Air National Guard.

Georgia Department of Defense: The Georgia Department of Defense is a state agency charged with coordinating and supervising all agencies and functions of the Georgia National Guard.  Headquartered at Clay National Guard Center in Marietta, Georgia, the Georgia Department of Defense includes the Georgia Army National Guard, the Georgia Air National Guard, and the Georgia State Defense Force.

Tom Moreland: Thomas D. Moreland, for whom the Tom Moreland Interchange is named, is one of the United States' leading road building experts, and has served as President of Moreland Altobelli Associates, Inc., since its inception in 1987.  Prior to organizing Moreland Altobelli, Mr. Moreland had a 30+ year career with the Georgia Department of Transportation, serving as Commissioner and/or Chief Engineer for the last 17 years.  In this capacity, he headed a department of 6,000 people, with an annual budget exceeding $1 billion.  While Commissioner of the Georgia DOT, Mr. Moreland served for 11 years on the Metropolitan Atlanta Rapid Transit Authority (MARTA) Board of Directors.  Mr. Moreland worked with the Georgia General Assembly annually on the drafting and reviewing of legislative proposals germane to the Georgia Department of Transportation’s goals and policies.  He also participated in the budgetary process and was successful in obtaining funding support for the Department’s multi-modal transportation program.

Georgia Department of Revenue: The Georgia Department of Revenue (GDOR) is the principal tax collection agency in the U.S. state of Georgia.  The Department administers tax laws and enforces laws and regulations concerning alcohol and tobacco products in the state.  The Georgia Department of Revenue is headquartered in Atlanta, Georgia

Georgia Army National Guard: The Georgia Army National Guard is the Army National Guard component of the Georgia National Guard, administratively part of the Georgia Department of Defense.  It consists of more than 11,100 citizen-soldiers training in more than 79 hometown armories and regional facilities across the state.  Georgia’s Army Guard is the eighth largest in the nation and includes combat, combat support and combat service support units.

Supporting paragraphs: Georgia Department of Defense Marietta, Georgia
Answer: Cobb County