The sloop Essex Junior was a French prize that the British whaling firm of Samuel Enderby and Sons purchased and used as a whaler under the name Atlantic.

She appears in the Register of Shipping in 1810 under the name Atalanta, with O. Gwyer, master, Enderby, owner, and trade London–South Seas.

[2] Captain Obed Wyer (or Gwyer, or Weir, or Wier) sailed from London on 12 April 1810 bound for Peru.

On 8 February 1814 Phoebe and Cherub arrived at Valparaíso, a neutral port, where Essex and her prizes were anchored.

A squall took off his main topmast and he attempted to return to harbour but Phoebe and Cherub drove Essex into a nearby bay and defeated her in a short engagement.

Porter took the view that the detention abrogated the cartel he had signed with Hillyer of Phoebe, and contrived to escape on shore.

The British released Essex Junior, and she sailed into harbour, past various forts that mistook her for an enemy ship and fired on her, without effect.