A gas turbine engine includes a turbomachine including a compressor section, a combustion section, a turbine section, and an exhaust section arranged in serial flow order and together defining at least in part a core air flowpath. The gas turbine engine also includes a thermal management system including a flowpath heat exchanger coupled to, or integrated into, one or more components of the compressor section, the combustion section, the turbine section, or the exhaust section such that the flowpath heat exchanger is directly thermally coupled to an airflow through the core air flowpath.