A ciphertext without its corresponding key was found in the archives from the Dutch colony Suriname, in the National Archives at The Hague. We were able to decrypt it through cryptanalysis and with the use of CrypTool2. The revealed plaintext contains a letter with military sensitive information and the name of Fredenburgh, who served as Governor ad interim from 1688 to 1689. It was sent in May 1689 by Governor Van Scharphuijsen to his directors in Amsterdam. Since 1689, the Society of Suriname (SvS) used ciphers for its militarily sensitive information. Ciphertext U3 was sent during the Nine Years’ War (1688-1697) when the Dutch were at war with the French. The letter was encrypted as a precaution against possible interception by the (French) enemy.