In the 1980s, a fleet hid beneath the Atlantic Ocean and attempted to conquer Earth, but were destroyed by the Sixth Doctor turning the Cybermen's dehydration weapons against them. (AUDIO: Hour of the Cybermen)
In 1988, though it may have done so through time travel, thousands of Cyber-Warships came to Earth seeking the Statue of Nemesis. With it, the Cyber-Leader planned to conquer the Earth and make it their base planet as the New Mondas, turning all humans into slaves.
When confronted by the Cybermen, the Seventh Doctor surrendered the Nemesis to them and launched the statue on the rocket-sled to meet with the Fleet as the Leader instructed. When the Nemesis reached the fleet in orbit of the Moon, having understood the Cyber-Leader's instructions and disobeying them, it exploded, destroying the entire Cyber-Fleet. (TV: Silver Nemesis)
The fleet was possibly destroyed during the Cyber-Wars, with the remnant Cyberman groups scattered across the Mutter's Spiral, forced to use ancient cyber-ships for travel. (TV: Revenge of the Cybermen)