Sinking a Secret was a virtual representation of one of Ratonhnhaké:ton's genetic memories, relived by Desmond Miles in 2012 through the Animus.
At some point, Connor was faced with a secret that would jeopardize the funding of the revolution. With this in mind, he was tasked to destroy the cargo of HMS Dartmoor, which had set sail for Boston.
The Dartmoor and its fleet were destroyed.
The Aquila defending against the gunboats
The Aquila sinking the Dartmoor