Scion of one of Europe's oldest extant monarchies, Prince Rainier III (born 1923) became the thirty-first ruler of Monaco in 1949. In the years since he has maintained the tiny Mediterranean principality as a prosperous slice of a bygone era, attractive to the rich and idle for its sunshine, lavish casino, and absence of income tax.

Rainier Louis Henri Maxence Bertrand de Grimaldi was born May 31, 1923 to Princess Charlotte, daughter of Monaco's reigning prince, Louis II. Rainier's father, Comte Pierre de Polignac, hailed from a venerable line of French aristocrats, but incited little but rancor in Louis II, a stern, military-loving monarch. Such intrafamilial conflicts were nothing new to the Grimaldi line, who possessed a long history of internal tumult. De Polignac and Charlotte's first child, Princess Antoinette, would one day conduct her own underhanded machinations in an attempt to seize power.

Treacherous Roots

At the time of Rainier's birth...