Ruled as elector of Prussia from 1640-1688; Frederick William had inherited the duchies of Brandenburg and Prussia. When he first began ruling Brandenburg was a very poor and rural area, which had been hit negatively by the Thirty Years War.
Frederick was able to achieve turning Prussia’s state from poor and struggling to a successful and thriving country. Other than turning around Prussia’s state he also created Germany’s first standing army, which was used to defend and grow his territory. To conclude, this was what Frederick William accomplished during his reign over Prussia.