The genesis of this work, Fire for Effect: Field Artillery and Close Air Support in the US Army, was the controversial decision in 2001 to deploy Army combat units to Afghanistan without their supporting field artillery units. Fire for Effect provides a historical survey of the relationship between field artillery and close air support (CAS) in the US Army since World War I. A recurring theme in this survey is the desire of air operators for independence in operations. This first occurs at the organizational level in the development of strategic bombing theories and forces. The desire for independence emerges also in Air Force doctrine which stressed the importance of interdiction over CAS missions. Eventually, the Army aviation community also sought independence in the idea of the independent strike of attack helicopters, known as the deep attack. This last concept became at least partially discredited in the sands of Iraq in 2003. Independent air operations contrast with the Army’s traditional combined arms concept where the arms and services work together to complement each other’s strengths and cover weaknesses. The field artillery has long been a key member of the combined arms team. The Army ground commander has controlled all the elements of this team except the fixed-wing close air support. Despite the differences in theory and practice, since the 1960s the two services have developed cooperative and coordinated systems that have solved most difficulties. Over these last 40 years, much progress has also been made with the development of precision guided munitions, giving both services the ability to use point fire weapons in their delivery of CAS. As this study shows, the introduction of sophisticated precision weapons has separated CAS from artillery, creating distinct and complementary systems of fire support. Both, however, remain necessary to give the ground commander responsive and powerful fires in the broad variety of combat situations that characterize the modern battlefield.