Battle of Molecay
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The Battle of Molecay was a major engagement between Cylon forces and the Fifth Fleet (including the Battlestar Pegasus), in which the Pegasus, under the command of Commander Cain, was apparently destroyed (Living Legend).
Cain and the Pegasus survived the encounter, and later meet up with the rag-tag fleet being lead by the Galactica, where Cain works to incite an attack on Cylon forces at Gamoray, against Adama's wishes. The Pegasus is again apparently destroyed in the battle (Living Legend).