There was a German poem about Frederick I that went like this:
Following the blood spilled by murderers, I carefully climbed the hill.
Corpses lay everywhere. The survivors rose, craning their necks, looking closely, searching closely.
Smoke rose all over the battlefield. They chose him as the Anointed One, God's messenger, the guardian.
The "Anointed One" here referred to Frederick I. Before him, Prussia had merely been an electorate. Frederick I crowned himself king, and from then on Prussia officially existed as a kingdom.
The Kingdom of Poland lay between East Prussia and Brandenburg, mainly because of the port of Danzig. During the First Partition of Poland, Frederick II annexed that port along with a vast stretch of land between East and West Prussia, joining the Kingdom of Prussia into one contiguous territory.
Intervening in Polish affairs and allowing Poland to reclaim Danzig and its lost lands could keep Prussia divided. That was also why the King of France had his eye on the Holy Roman Empire: it would make it easier to defeat them one by one. Yet military and diplomatic victories were only temporary.
There was such a case. In 1733, Augustus II, King of Poland, died, leaving the Polish throne vacant. The War of the Polish Succession broke out immediately afterward. France, Spain, the Kingdom of the Two Sicilies, and Prussia entered the war in succession. A Prussian colonel named Andreas Joachim was killed in that war. His widow, Elizabeth, inherited his estate by Kaiser Lake and reclaimed the debts her husband had lent out through the Berlin courts.
She invested the money in reputable local credit institutions, or lent it to neighbors at five percent interest. She accepted deposits from all walks of life, ran the family estate as a business, and supervised matters large and