mainly of splitting the casings open to release the pressure inside and terminate thrust. The ISDS would end up being used a few times over the Titan's career. Another slight modification to SRB-equipped Titans was the first stage engines being covered instead of the open truss structure on the Titan II/IIIA/IIIB. This was to protect the engines from the heat of the SRB exhaust. Titan III/IV SRBs were fixed nozzle and for roll control, a small tank of nitrogen tetroxide was mounted to each motor. The would be injected into the SRB exhaust to deflect it in the desired direction. As the IIIC consisted of mostly proven hardware, launch problems were generally only caused by the upper stages and/or payload. The second launch in October 1965 failed when the Transtage suffered an oxidizer leak and was unable to put its payload (several small satellites) into the correct orbit. The third launch in December experienced a similar failure. The fourth IIIC launch was used to send the LES 4 (Lincoln Experimental Satellite 4) into orbit. It was a US Air Force experimental communications satellite launched along with OV2-3, LES 3, and Oscar 4 from Cape Canaveral aboard a single Titan 3C rocket. It transmitted in X-band. The fifth Titan IIIC (August 26, 1966) failed shortly after launch when pieces of the payload fairing started breaking off. Around 80 seconds, the remainder of the shroud disintegrated, causing loss of launch vehicle control as well as the payload (a group of IDCSP satellites intended to provide radio communication for the US Army in Vietnam). The ISDS activated automatically when one of the SRBs broke away from the stack and destroyed the entire launch vehicle. The exact reason for the shroud failure was not determined, but the fiberglass payload shrouds used on the Titan III up to this point were replaced with a metal shroud afterwards. A Titan IIIC in November 1970 failed to place its missile early warning satellite in the correct orbit due to a Transtage failure and a 1975 launch of two DSCS II military communication satellites left in LEO by another Transtage failure. On March 25, 1978, a launch of two DSCS II satellites ended up in the Atlantic Ocean when the Titan second stage hydraulic pump failed, resulting in engine shutdown approximately 470 seconds after launch. The Range Safety destruct command was sent, but it was unclear if the