The operation_sealion.zip file you have requested: Maps / Conquest / Operation Sealion - 18.8mb is not available. Perhaps try browsing all files for the game Battlefield 1942 and upload any files you want to share or are missing. This is the only information we could locate:
A map for Battlefield 1942 about Germany's invasion of England that never happened. As of yet there is no single player in the map, but RussianComrade is working on that.