Shortly after deployment and final field testing of the Ambassador, a large number of these vessels were launched. Among them was the USS Enterprise (NCC-1701-C), the fourth Federation starship to bear the name. She was commanded by Captain Rachel Garrett. From 2335 until 2344, the Enterprise-C was given a five-year exploratory mission. Both during and after the exploratory mission, the ship was assigned several diplomatic missions in support of the Federation-Klingon peace treaty, Klingon membership in the Federation, and Federation relations with the Cardassian Empire prior to the Federation-Cardassian War. Much of the ship's history remains classified due to its impact upon Federation security.

In late-2344, the Enterprise-C received a distress call from the Klingon outpost on Narendra III, a planet near the Romulan border. The outpost was under attack by four Romulan Type-A warbirds. The Enterprise-C was the only Federation ship in range at the time. She went in and joined a Klingon bird-of-prey to try to defend the colony. The Enterprise-C was hit by a multiple barrage of photon torpedoes, and the extreme energy discharge from the exchange of fire created a temporal rift around the ship. This caused the vessel to be thrown twenty-two years into the future and altered the course of history. In the alternate timeline, the Federation had been at war with the Klingon Empire for nearly two decades and was close to losing the conflict. The alternate version of the Galaxy class heavy cruiser USS Enterprise (NCC-1701-D) encountered the Enterprise-C when she emerged from the temporal rift. The alternate Captain Jean-Luc Picard and his Enterprise-D crew protected the ship and helped it re-enter the rift to send it back to its own time to restore history. In the end the Enterprise-C was destroyed by the Romulans. [Editor's note: Refer to the Star Trek: The Next Generation episode "Yesterday's Enterprise" for more information.]

Another Ambassador class vessel is the USS Excalibur (NCC-26517), the second Federation starship to bear the name. The first appearance of this vessel takes place in the Star Trek: The Next Generation episode, "Redemption, Part II". The ship was used in the armada assembled by Captain Jean-Luc Picard of the USS Enterprise to block a shipment of supplies from the Romulans to the forces of the Duras house during the Klingon civil war of 2368. The ship did not have a captain or first officer at the time, so Commander William Riker and Lieutenant Commander Geordi La Forge (respectively first officer and chief engineer of the Enterprise) were assigned those positions for the duration of the mission.

The next appearance of the Excalibur took place during Star Trek: First Contact. Captain Paul Korsmo commanded the ship during the second Borg incursion of Federation space, and the ship was involved in the firefight in Sector 001. Commander Elizabeth Shelby was his first officer. Korsmo received fatal injuries in the line-of-duty and died shortly after the battle. Under his command, Excalibur successfully inflicted damage to the Borg cube and managed to vacate the combat zone before the Borg had the opportunity to destroy it.

Captain Mackenzie Calhoun was given command of the Excalibur several months after the incident with the Borg. Commander Shelby remained as his first officer. Starfleet assigned the vessel to a mission of patrolling and serving as diplomatic liaison to the new frontier region that resulted from the collapse of the Thallonian Empire just outside Federation space. [Editor's Note: Refer to the film and the new novel series Star Trek: New Frontier by Peter David for more information.]

The USS Horatio (NCC-10532) was an Ambassador class starship commanded by Captain Walker Keel, an old friend of Captain Jean-Luc Picard and Chief Medical Officer Beverly Crusher of the USS Enterprise (NCC-1701-D). The Horatio met the Enterprise and the New Orleans class frigates USS Renegade and USS Thomas Paine at the Federation mining colony on Dytallix B in 2364. The starship captains met on the planet to discuss the possibility of an alien infiltration of Starfleet Command at its highest levels. When the invading aliens learned of this meeting, they destroyed the Horatio. The sudden and total destruction of Keel's starship made Captain Picard suspicious, so he took the Enterprise back to Earth where he and his crew eventually located the aliens and eliminated them. [Editor's note: Refer to the Star Trek: The Next Generation episode "Conspiracy" for more information.]

The USS Adelphi (NCC-26849) is an Ambassador class ship that was assigned the diplomatic mission of making first contact with the planet Ghorusda. The assignment was a disaster that resulted in the deaths of Adelphi Captain Darson and forty-six other individuals. A Starfleet board of inquiry found that Captain Darson was at fault for causing the mission's failure. He had greatly offended and angered the Ghorusdans by disregarding some of their cultural taboos. Betazoid mission specialist Tam Elbrun may also have been at fault for not warning Darson about the Ghorusdans' hostile natures. [Editor's note: Refer to the Star Trek: The Next Generation episode "Tin Man" for more information.]

The USS Zhukov (NCC-62136) is commanded by Captain Gleason, and Lieutenant Reginald Barclay was stationed aboard this ship before his transfer to the engineering division of the USS Enterprise (NCC-1701-D) in 2366. The vessel transported the former Federation ambassador T'Pel (who was actually a Romulan spy) to the Enterprise-D in 2367. When the Enterprise-D needed more science personnel for its mission at the Phoenix Cluster in 2368, the Zhukov transferred several groups of qualified specialists to that starship. [Editor's note: Refer to the Star Trek: The Next Generation episodes "Hollow Pursuits", "Data's Day", and "The Game" for more information. The Zhukov was named in honor of Russian General Grigori Konstantinovich Zhukov (1896-1974).]