Charles Cobby, whose surname is also recorded as Cobbey, was born in England and migrated to Victoria, Australia. Upon arriving in Australia, very likely in Melbourne, Cobby settled down in a community on the outskirts of Melbourne. In February Cobby became aware, as did many in Melbourne, that a Confederate Cruiser, the famous Rebel Raider "CSS Shenandoah", had arrived in Port Phillip Bay, off Melbourne on January 25, 1865, to make necessary repairs to her propeller shaft, recalk her weather beaten hull and to resupply her store supplies before resuming attacks on Union merchant and whaling ships at sea. Learning that the "Shenandoah" was also looking for deck hands, though it was not legal to do so in a neutral port, Cobby decided to take a look at the ship for himself. It was while he was doing so that he decided he too would like to join her crew.

Shortly before midnight on the night of February 17, 1865, Cobby made his way to the Williamstown dock where she was berthed, and silently slipped aboard the "Shenandoah"; being assisted by crewmembers in hiding away until the "Shenandoah" left port. To be discovered meant removal from the ship and his arrest. Once the "Shenandoah" was at sea and out of Australian waters, Cobby came out of hiding and officially signed aboard the "CSS Shenandoah" with others who had likewise stowed away. Cobby signed aboard as a seaman, on February 18, 1865, placing his mark beside his name, for the pay of $29.10. Later, on March 27, 1865, after proving his worth to the Captain, Cobby's rating was changed from that of a seaman to that of a Petty Officer as a quarter gunner's mate. Cobby also became one of the signatories who expressed their confidence in the command of Lieutenant James I. Waddell, in a petition dated September 1865.

After the surrender of the CSS Shenandoah on November 6, 1865 to British Captain Paynter, commanding her Majesty's ship "Donegal, at Liverpool, England, Cobby joined the rest of the crew ashore; being paroled and given temporary quarters in Liverpool.