What country was Wroclaw a capital of?
The conquest of Silesia was such a significant gain to the Kingdom of Prussia that shortly after Wroclaw (known as Breslau at the time) was elevated to the third capital of the state alongside Königsberg and Berlin. The official title was the Royal and Residential City of Wroclaw (ger. Königliche Haupt- und Residenzstadt Breslau).
Answers by country
the United Kingdom