This paper reviews the history and development of modern optimal control and robust control. It begins by noting that while robust control was initially seen as a reaction to the limitations of optimal control, the distinction has largely disappeared, with optimal control methods now central to robust control theory, especially in H-infinity theory. The paper then traces the evolution of robust control from the 1970s to the 1980s, highlighting the introduction of H-infinity methods to address plant uncertainty and the development of robust stability criteria. The 1980s saw significant progress in H-infinity control theory, with the development of controller synthesis techniques based on state-space methods and the use of Riccati equations. The paper also discusses the rise of H-infinity control and its connections to other areas of modern control theory, such as risk-sensitive control, differential games, and J-lossless factorization. It notes that while H-infinity theory has become dominant, other topics like L1, mu, real parameters, and robust modeling remain important but have less direct connections to optimal control. The paper concludes by emphasizing the importance of H-infinity theory in robust control and the progress made in addressing robust performance issues, including the integration of H2 methods with H-infinity frameworks. The paper also highlights the role of state-space techniques and the use of linear matrix inequalities (LMIs) in robust control. Overall, the paper provides a comprehensive overview of the development and significance of H-infinity theory in modern control.This paper reviews the history and development of modern optimal control and robust control. It begins by noting that while robust control was initially seen as a reaction to the limitations of optimal control, the distinction has largely disappeared, with optimal control methods now central to robust control theory, especially in H-infinity theory. The paper then traces the evolution of robust control from the 1970s to the 1980s, highlighting the introduction of H-infinity methods to address plant uncertainty and the development of robust stability criteria. The 1980s saw significant progress in H-infinity control theory, with the development of controller synthesis techniques based on state-space methods and the use of Riccati equations. The paper also discusses the rise of H-infinity control and its connections to other areas of modern control theory, such as risk-sensitive control, differential games, and J-lossless factorization. It notes that while H-infinity theory has become dominant, other topics like L1, mu, real parameters, and robust modeling remain important but have less direct connections to optimal control. The paper concludes by emphasizing the importance of H-infinity theory in robust control and the progress made in addressing robust performance issues, including the integration of H2 methods with H-infinity frameworks. The paper also highlights the role of state-space techniques and the use of linear matrix inequalities (LMIs) in robust control. Overall, the paper provides a comprehensive overview of the development and significance of H-infinity theory in modern control.