was he married?
Yes, more than once
Mieszko I
According to Gallus Anonymus, before becoming a Christian Mieszko had seven pagan wives, whom he was required to relinquish, leaving Dobrawa as his only spouse. 
when did the third silesian war take place? 1756 to 1763 between whom did it happen? Between Prussia and Austria where did it begin? The war was fought mainly in Silesia, Bohemia and Upper Saxony where is the first one located? It is a historical region of Central Europe mostly in Poland, with small parts in the Czech Republic and Germany. where did the first country get it's name from? The origin of the name "Poland" derives from the West Slavic tribe of Polans ("Polanie") was it under the reign of any king? Under the Piast dynasty, Poland's first historically documented ruler, Mieszko I was he a part of any war? German civil war
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Mieszko I [SEP] Marriages and issue
According to Gallus Anonymus, before becoming a Christian Mieszko had seven pagan wives, whom he was required to relinquish, leaving Dobrawa as his only spouse. Nothing is known of the fates of any possible children from these relationships. In 965, before his baptism, Mieszko married Dobrawa (b. 940/45 – d. 977), daughter of Duke Boleslav I the Cruel of Bohemia. They had two children: According to one hypothesis there was another daughter of Mieszko, married to a Pomeranian Slavic prince; she could be a daughter of Dobrawa or of one of the previous pagan wives. According to one theory, this unnamed daughter of Mieszko I and her Pomeranian husband were the parents of Zemuzil, Duke of Pomerania.