The mission of Ambassador Paweł Działyński to Queen Elizabeth in the summer of 1597, conducted on behalf of Sigismund III, King of Poland, and the City of Gdańsk, is usually presented by scholars relying exclusively on English records as an embarrassment to Poland-Lithuania. However, the Polish point of view, expounded at length in the Ambassador’s account of the embassy, gives an entirely different picture and interpretation of the events, far more consistent with the practical outcome for relations between the two states in the following years. The full original manuscript of Mercurius Sarmaticus survives in a major Polish library, and copies are extant elsewhere in Europe. Of particular interest are Działyński’s observations on Elizabeth and the religious situation in her realm. Mercurius Sarmaticus also throws light on the Isle of Dogs incident in the history of the Elizabethan theatre and may be regarded as a Shakespeare source. This article will provide an introduction to the manuscript source, a synopsis of its content, and English translations of selected passages.