Frederick-I was elector of Brandenburg, who became the first king in Prussia, freed his domains from imperial suzerainty, and continued the policy of territorial aggrandizement begun by his father.

Frederick was noted for his opposition to France, in contrast to his father who had sought an alliance with Louis XIV. Frederick took Brandenburg into the League of Augsburg against France and in 1689 led military forces into the field as part of the allied coalition. That year an army under his command besieged and captured Bonn. Despite this opposition to France (a characteristic that was even more prominent in his son and heir) he was fond of French culture and styled his court in imitation of that of Louis XIV.

His grandson, Frederick the Great, referred to Frederick I as "the mercenary king", due to the fact that he greatly profited from the hiring of his Prussian troops to defend other territories, such as in northern Italy against the French.

The above-shown coin issued under his reign in 1691. The obverse of a coin depicts the king’s bust while the reverse of a coin represents the coat of arms.

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