what was its prime cause?
Brandenburg–Prussia's ruling House of Hohenzollern held dynastic claims to various duchies within the Habsburg province of Silesia
Context and causes
Brandenburg–Prussia's ruling House of Hohenzollern held dynastic claims to various duchies within the Habsburg province of Silesia, a populous and prosperous region contiguous with Prussia's core territory in the Margraviate of Brandenburg. 
when did the first silesian war take place? 1740 where? Silesia, Moravia and Bohemia between whom? Prussia and Austria
Centuries-old territorial disputes between the two with Realpolitik and geostrategic factors provoking the conflict; and Maria Theresa's controversial succession to the Habsburg monarchy, thereby strengthening Prussia's position vis a vis to its regional rivals. No particular triggering event started the war. Prussia cited its centuries-old dynastic claims on parts of Silesia as a "casus belli", but "Realpolitik" and geostrategic factors also played a role in provoking the conflict.
First Silesian War First Silesian War First Silesian War
Introduction Introduction Introduction
No particular triggering event started the war. Prussia cited its centuries-old dynastic claims on parts of Silesia as a "casus belli", but "Realpolitik" and geostrategic factors also played a role in provoking the conflict. Maria Theresa's contested succession to the Habsburg Monarchy provided an opportunity for Prussia to strengthen itself relative to regional rivals such as Saxony and Bavaria. No particular triggering event started the war. Prussia cited its centuries-old dynastic claims on parts of Silesia as a "casus belli", but "Realpolitik" and geostrategic factors also played a role in provoking the conflict.
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First Silesian War [SEP] Context and causes
In the early 18th century, Brandenburg–Prussia's ruling House of Hohenzollern held dynastic claims to various duchies within the Habsburg province of Silesia, a populous and prosperous region contiguous with Prussia's core territory in the Margraviate of Brandenburg. Besides its value as a source of tax revenue, industrial output (particularly minerals) and military recruits, Silesia held great geostrategic importance to the belligerents. The valley of the Upper Oder formed a natural military conduit between Brandenburg, the Kingdom of Bohemia and the Margraviate of Moravia, and whichever power held the territory could threaten its neighbours. Silesia also lay along the north-eastern frontier of the Holy Roman Empire, allowing its controller to limit the influence of the Polish–Lithuanian Commonwealth and of the Russian Empire within Germany.