These ships transporting enslaved people were also captured as prizes during the naval wars, and documents and artefacts were seized from them and used as evidence in the consecutive court proceedings. We have just published extensive material from two ships involved in the slave trade for the first time. These are several thousand documents that anyone interested can view open access – and documents and artefacts obtained from more ships will follow. In future, these documents from the Prize Papers, which originate from captured ships that were involved in the slave trade, will also be available in the international database of the "Slave Voyages" project, with which the Prize Papers team has recently started co-operating. Moreover, the Prize Papers project is currently presenting selected examples of documents and objects in large-format photographs in an exhibition in Berlin.

In the trials before courts of the high admiralty, slavery was not condemned, but negotiated – with enslaved people treated like any other goods. Because of the prize-system, sailors who had captured a ship and its cargo could claim ownership of the enslaved people on board. For example, a British commander would argue that these people were part of a legitimate 'prize'. If the court later ruled the capture was legal, the enslaved people were declared "enemy property" and sold at auctions. Few documents mention enslaved people by name and only in exceptional cases did they have their say in court.

People were also bought in exchange for colourful glass bead necklaces, known as slave beads, for example in Elmina Castle in present-day Ghana, a Dutch trading hub that mainly sold enslaved people for onward transportation to America. Artefacts such as glass beads have also been preserved in the Prize Papers – for example a glass bead necklace that was on its way from Elmina to Amsterdam as a sample for future orders in 1803, when the ship "Diamond" carrying this letter was captured.

Glass jewellery of this kind is still worn in Ghana today and carries a high emotional value, as we were able to learn from the Ghanaian researcher Sarah Tam. It is important to contextualise these artefacts. The same applies to two gold signet rings that have been preserved in unopened letters in the archived captured goods from on board the "Diamond".

These rings are in remarkable condition for being over 200 years old – they look like new. The sealed accompanying letter in which they were enclosed contains important details about the jewellery. The author, J.G. Coorengel, writes from Elmina to his mother in Amsterdam. To comfort her after her father’s death, he sent her the locally made rings. They were made by Ghanaian artisans who were most likely enslaved.

First-hand accounts from enslaved people are very rarely preserved in the archives – but they do exist. For example, while researching trial records from the Prize Papers collection, we came across "Caesar", who was born into slavery in Maryland, as he himself stated on the record. When British privateers captured the ship "Priscilla" sailing under the flag of the "secessionist" colonies during the American War of Independence, Caesar was on board. The New York Vice Admiralty Court took his statement, and as he could neither read nor write, Caesar signed it with an x, next to which is the note "Caesar his mark".

Although slavery was outlawed in Europe, it was possible to circumvent the ban. For example, a document signed by the French governor of Martinique allowed for an enslaved ten-year-old named "Scaramouche" to be shipped to France. The name was given to him by his owner; his real name is unknown. But we do know from the document that he came from the kingdom of Arada in Benin. According to the letter, the boy was destined for the widow Charron in Nantes, who wanted to "teach him a trade and educate him in the Catholic religion" before sending him back. His fate, especially after the capture of the ship, remains unknown.