History 20 Politics and government 8 Terrorism 6 World War, 1939-1945 5 Biography 3 Campaigns 3 Communication 3 Foreign relations 3 Industrial management 3 Juvenile literature 3 Leadership 3 National security 3 Naval operations 3 Personal narratives, American 3 Prevention 3 Afghan War, 2001 2 Armed forces 2 Civil War, 1861-1865 2 Combat 2 Computer networks 2 English language 2 Generals 2 International relations 2 Interpersonal relations 2 Language 2 Macroeconomics 2 Management 2 Naval operations, American 2 Navies 2 Organizational behavior 2