On November 14, 2008, the Compact Muon Solenoid (CMS) successfully generated a nominal magnetic field of 4 tesla. This success rewards IRFU efforts for the design and construction of what constitutes the largest superconducting solenoid magnet in the world. Over a period of approximately one month, CMS teams conducted a continuous data acquisition campaign with the detector operating under nominal conditions. Approximately 300 million cosmic events were recorded. This also provided an excellent opportunity to showcase the specific expertise of IRFU teams, particularly in areas such as detection systems, electronics, trace data reconstruction techniques and laser control systems.