The USS Exeter was a Federation Class J starship in service in the 23rd century. By 2266, its design was considered old. In that year, while under the command of Captain J. Mia Colt, it hosted a cadet training exercise supervised by Fleet Captain Christopher Pike. (TOS comic: "Captain's Log: Pike")
Commodore Jose Mendez became concerned when he learned that Pike, his close friend, was accompanying the training mission. He had doubts regarding the material fitness of the aging starship type, and was particularly worried for the safety of his friend. (TOS novel: Burning Dreams)
Shortly after the Exeter cleared the asteroid belt on its cruise, it received an alert signal from Europa Base. A Halogian starship had been detected moving toward Jupiter at high speed. Despite being poorly shielded and equipped with few weapons, the Exeter was the only ship close enough to respond. On Captain Colt's orders, the ship engaged an intercept course with the Halogian vessel. (TOS comic: "Captain's Log: Pike")
The Exeter's crew discovered that the Halogians were using a radiation beam in an attempt to ignite stellar fusion in Jupiter's core. The Exeter engaged the Halogians, and quickly suffered significant damage. While Captain Colt commanded her ship from the bridge, Fleet Captain Pike responded to an emergency in engineering, where twenty-three cadets were attempting to keep the ship together, but lacked the expertise necessary to ensure their own safety. Just as the Halogian ship was destroyed, the baffle plates in engineering ruptured, flooding the compartment with dangerous radiation. Captain Pike was badly irradiated, but he saved the cadets in engineering. He was the Exeter's only casualty. (TOS comic: "Captain's Log: Pike")
- In the novel "Burning Dreams," three instructors and fifteen cadets perished in the accident. Eighteen others, including Fleet Captain Pike, were injured, burned or irradiated. All of the survivors except Pike fully recovered.