The Ambassador-class had entered Starfleet service by the 2340s. One noteworthy Ambassador-class ship was the USS Enterprise-C. In 2344, while under the command of Captain Rachel Garrett, this ship responded to a distress call from a Klingon colony on Narendra III, which was under attack by four Romulan warbirds. The Enterprise responded to the attack, and despite being destroyed there, defended it long enough to impress the Klingon High Council; this act of bravery in combat was seen as extremely honorable, thus securing a treaty between the Klingon Empire and the Federation. (TNG: "Yesterday's Enterprise")
Several ships of the Ambassador-class served during the 2360s and saw action during the Battle of Wolf 359 and the Klingon Civil War. The class was still in use by 2369. (TNG: "Redemption II", "Aquiel"; DS9: "Emissary")
The Ambassador-class featured the saucer section-engineering section-warp nacelle layout common to most Starfleet vessels. It was intermediate in size between the Excelsior-class and the Galaxy-class. In addition, the class boasted at least three engineering levels. (TNG: "Yesterday's Enterprise")
A number of Ambassador-class ships were constructed with minor alterations from the original design. The saucer section's connection to the engineering hull was shifted slightly aft, with the nacelle pylon assembly moved a corresponding distance in the same direction. Cowlings were added around the Bussard collectors, making them appear closer to that of the Galaxy-class, while the impulse engine exhaust changed from a blue to a red glow. The lower sensor dome became more elaborate and closer in appearance to the Excelsior-class and the deflector dish was modified. Finally, the width of the shuttlebay was increased and a second facility resembling that on the Excelsior-class engineering hull was mounted directly underneath the original one. Graphics were upgraded with the Starfleet insignia of the 2360s. (TNG: "Data's Day"; DS9: "Emissary")
Families were allowed aboard Ambassador-class ships, but only if they were related to a Starfleet crewmember who had served on the ship exceeding six months. (TNG: "Second Chances") The crew capacity far exceeded one hundred twenty-five. (TNG: "Yesterday's Enterprise")
According to Natasha Yar, during the 2340s, the Ambassador-class had "a lot more maneuverability than the Romulan counterparts of that era." Yar went on to explain that in her alternate timeline, deflector shield technology of the 2360s had advanced considerably during the war, allowing the Galaxy-class to possess a heat-dissipation rate that was almost double those of the Ambassador-class, allowing the Galaxy to hang in a firefight longer. (TNG: "Yesterday's Enterprise")
Primary operational control of the Ambassador-class starship was provided by the main bridge. Located on top of the primary hull, the bridge directly supervised all primary mission operations and coordinated all departmental activities.
In 2344, the central area of the bridge provided seating for the captain only. Directly fore and to the right of the captain was the ops station, with the helm station to the left. The consoles were similar to that used on the bridges of Excelsior- and Galaxy-class starships. At the very front of the bridge was a large viewscreen, with a freestanding console located directly below. Against the back walls of the bridge were consoles for the tactical, engineering, and science positions. Additional displays flanked the aft consoles. The bridge was accessed through two doors, located on the forward halves of the port and starboard walls. (TNG: "Yesterday's Enterprise")
The original design incorporated flat-panel, LCARS-based, control panels using the interface introduced in the late 23rd century. (TNG: "Yesterday's Enterprise") By the 2360s, the Ambassador-class bridge was upgraded to include the standard LCARS interface and consoles typically found on board modern vessels of that era. (TNG: "Redemption II")
- USS Enterprise (NCC-1701-C)
- USS Excalibur (NCC-26517)
- USS Horatio
- USS Yamaguchi (NCC-26510)
- USS Zhukov (NCC-26136)
The Ambassador-class designation dates back to an early script draft of "Patterns of Force", which described the source of cultural contamination arriving aboard a small Ambassador-class vessel called the Magellan. The term was later used in "Conspiracy" to describe the starship Horatio. It was connected to the Enterprise-C design on display graphics in "Yesterday's Enterprise."
Andrew Probert has stated that his original concept is precisely 1,720 feet long (524.256 meters). The number is consistent with an early TNG size comparison chart, also provided by Probert, although he did not write the 1,721-foot callout on that drawing.  
The first and subsequent editions of the STE popularized a length of 526 meters for Rick Sternbach's final design. Several years before the Star Trek Encyclopedia was published, the number had been added to Star Trek: The Next Generation Writers' Technical Manual, which also gives an imperial equivalent of 1,725 feet.
Gary Kerr calculated a second figure of 1,570 feet and a metric conversion of 478.5 meters, explaining that the Enterprise-C is just short of 35.75 inches long in the blueprints of its miniature, and that the blueprints are in scale with the four-foot miniature of the Enterprise-D. Kerr used 2,108 feet for the length of the latter and 48 inches for the length of the four-foot miniature, although he also determined that it was probably closer to 49.25 inches long. Nevertheless, Rick Sternbach fully supports the 1,570-foot calculation, saying that he worked with the same assumptions when drafting the Enterprise-C blueprints.
Aside from the unexplained figure of 526 meters, it is unclear whether the size implied by Rick Sternbach was deliberately changed during the original development process. His initial full-scale blueprints were blown up by 15%, which means that the final size of the miniature (41.19 inches) could have influenced the ship's conceptual size next to the Enterprise-D. Greg Jein also did not recall scaling up the blueprints, nor who did.
The Star Trek: The Next Generation Technical Manual (p. 75) explained that during the design phase, the combined vehicle mass of Ambassador was expected to be at least 3.71 million tons.
- See main article: Ambassador-class model
Ships of the Line calendar
- Category: Explorer / Emissary
- Length: 524.256 meters [1,720 feet]
- Width: 283.006 meters [928 feet, 6 inches]
- Height: 101.955 meters [334 feet, 6 inches]
- Mass: 3,710,000 metric tons
- Number of Decks: 33
- Officer crew: 320
- Enlisted crew: 1,000
In non-Trek related media, a cartoon version of the Ambassador-class vessel appeared in an episode of the Cinar-Paramount animated series The Busy World of Richard Scarry. A Futurama parody of an Ambassador-class, with Scott Bakula at the helm, also appeared in the direct-to-DVD film Bender's Game.
The Ambassador-class ships Excalibur and Zhukov make appearances in the Star Trek: Bridge Commander PC game.
The Ambassador-class was released as a playable starship as part of the third anniversary for the game Star Trek Online. In the game, the player gets the opportunity to take command of the USS Enterprise-C after she winds up in the 25th century instead of returning to Narendra III at the end of "Yesterday's Enterprise". The altered Ambassador-class seen in "Data's Day" and "Emissary" is an alternate skin in the Fleet version of the Ambassador-class and is referred to as the Yamaguchi-class (β), named after the USS Yamaguchi lost during the Battle of Wolf 359. A variant of the Ambassador-class based on Andrew Probert's original design was later included, christened the Narendra-class (β) after the planet where the Enterprise-C was lost.
In Star Trek: Legacy the Ambassador-class is a playable Federation ship.