Star Trek: Every Starfleet Starship Class Ranked Worst To Best
65. Apollo
The Apollo class was something of a forerunner and descendant of the Vulcan ships that were seen in Star Trek: Enterprise. The warp drive was based on a circular, or at least, enveloping style of warp nacelle - rather than the standard separate nacelles. This is similar to the D'Kyr and Surak class ships of the 22nd century.
The Apollo class were seen only as, it later transpired, troop carriers for a Romulan invasion force. The mission was due to take over Vulcan and force a reunification between the two races, though under the boot of a Romulan Praetor.
However, once this was uncovered by Captain Picard, Lt. Commander Data and Ambassador Spock, the three vessels that were en route to Vulcan were quickly destroyed by a hidden Romulan Warbird. This ensured that the troops would not be captured - and war was averted.