Complex sentence: Advance of the Russian coastal squadron beyond Hangö created difficulties for the Swedes since after the loss of the archipelago fleet at Sveaborg even that detachment equaled in strength the Swedish coastal forces deployed to Finnish archipelago.
Split into simpler sentences: Advance of the Russian coastal squadron beyond Hangö created difficulties for the Swedes. After the loss of the archipelago fleet at Sveaborg even that detachment equaled in strength the Swedish coastal forces deployed to the Finnish archipelago.