On 1st January 1867 the Caboceer docked at Aveiro in Portugal and in the afternoon the crew members were given leave to go ashore by the captain. That evening, back on the vessel, a dispute arose over ownership of a quantity of eggs that had brought aboard. This ended with 36 year old first mate Evan Matthias pulling the hair of able seaman Miles Dempsey, with so much force that his head bled. He then dragged Dempsey onto the deck and knelt on his chest with great force and hit him with a belaying pin.
Ten days later, twenty year old Dempsey complained of pains in his chest and was unable to resume his duties. He remained bedbound until the vessel arrived at Liverpool's King's Dock on 23rd February. He was taken to the workhouse hospital while Matthias was arrested and charged with assault. On the 28th Dempsey died, leading to Matthias being committed for a manslaughter trial at the assizes.
At the trial on 29th March evidence was heard that Matthias claimed all of the eggs were his, while other crew members had said they were to be shared out equally. It was also heard that Dempsey had a cold when he joined the Caboceer and this worsened when he spent a night on deck in the rain. The workhouse doctor said that he had dropsy and exhaustion, with a postmortem revealing chronic disease in the heart. In his opinion, death was accelerated by excitement occasioned by the assault.
After the jury returned a verdict of guilty, sentence was deferred until the following day. Mr Justice Mellor told Matthias that taking all factors into consideration, Dempsey would probably not have died if he was in good health. However, he added that the jury had come to the right conclusion in points of law and that violence on ships was too common. He then imposed a sentence of five months imprisonment with hard labour.