Complex sentence: To cross the 300 km of the Baltic Sea, Marcel des Moulinais Brindejonc had obtained from the Russian navy, with the prince Liben, eight destroyers were placed on 25 June every eighteen miles between the island and Argo the Swedish capital.
Split into simpler sentences: To cross the 300 km of the Baltic Sea, Marcel des Moulinais Brindejonc had obtained eight destroyers from the Russian navy. On 25 June these were placed every eighteen miles between the island and the Swedish capital.