(FORTUNE Magazine) – The extraordinary talents required to build wealth of billions are the same in Germany as elsewhere. But preserving family money through decades of hyper- inflation, fascism, and defeat in two world wars is a special kind of challenge. The family bank run by August von Finck and his older brother, Wilhelm, was founded in the 1870s, a time when 1,200 of them flourished. Today there are fewer than 100, and none comes close to the von Fincks' for reach and power. The brothers preside over Europe's largest private banking fortune because their father, August Sr., was a workaholic determined with single-minded zeal to safeguard his wealth. He managed to rebuild Merck Finck & Co. after the war despite tremendous handicaps. One was of his own making -- a five-year suspension from running the bank because of old Nazi ties. A stern reactionary in the 1930s, he had seen Hitler's National Socialist movement as a last bulwark against decadence and radical unrest. He raised funds to build Munich's grandiose Haus der Kunst museum, a pet project of Hitler's to house the artworks of his thousand-year Reich. For his party loyalty, von Finck was chosen to ''Aryanize'' the Rothschild bank in Vienna after Hitler swept into Austria in 1937. Back in control of his own bank in 1951, von Finck steered a conservative course that helped him avoid the fate of scores of other private German bankers who were forced to sell out to larger money center banks. By the time of his death in 1980 at his desk in his forest-enshrouded country estate outside Munich, a former cloister called Gut Moschenfeld, the 82-year-old von Finck was Europe's richest banker and turned over to his sons an empire with a net worth of some $1.2 billion. The loving attention he lavished on his fortune, however, did not extend to his family. Old August was a penny-pinching tyrant. He had his hair chopped by a country barber, puffed cheap cheroots, and maintained a decades-long loyalty to a battered Volkswagen Beetle. Twice married, he subjected his five children to a Teutonic version of ''daddy dearest,'' tightfisted and demanding, cold and remote. Though August Sr. brought his two older sons into the bank and made them partners, they lived in his shadow, ignored and little known in German banking circles until after the old man's death. Since coming into their inheritance, Wilhelm, 59, who preferred to live in Dusseldorf at a safe remove from Papa's supervision, has let brother ''Gustl'' (pronounced GOOST-el), 57, run the bank as chairman from its Munich headquarters. Half-brothers Gerhard, who trained as a stockbroker in Canada, and Helmut, a former devotee of Oregon's guru Bagwhan Rashneesh, settled their claims on the estate for cash and play no management role in the family businesses. Together with a cousin, Wilhelm Winterstein, and a fourth partner named Adolf Kracht, a seasoned banker recruited from one of Germany's big banks, Gustl and Wilhelm are giving old August's bank plenty of forward spin. The partners reckon that over the coming decade the billions of dollars in loans that German businessmen and private citizens borrowed to finance the country's postwar reconstruction will be paid off, creating deep new pools of liquidity that will have to be managed. By offering financial consulting services, private placements, and fee- generating asset management, they intend to spearhead a new golden age of private banking. ''Our size and lower overhead allow us to offer more custom- tailored, individual banking services,'' says partner Kracht. ''As traditional European bankiers, we are liable to our last trouser button, which gives our clients the greatest possible guarantee that their investments will be ) prudently managed.'' Since implementing the new strategy in 1981, Merck Finck's assets have grown an average annual 6%, to $1.8 billion in 1986. Though their riches could support a sumptuous lifestyle that would have turned Bavaria's spendthrift Mad King Ludwig green with envy, the brothers Finck live plain, middle-class lives. Both favor well-tailored, bankerly attire in contrast to their father's rumpled off-the-rack suits, and drive sleek Mercedes sedans rather than battered Beetles. But habits of thrift enforced by their parsimonious parent have left a lifelong imprint. Shy about being photographed, partly out of fear of kidnappers, August Jr. and his wife, Francine, shun the glittery society of Munich's Schickeria. They prefer quiet weekend country outings with their four young children, picking mushrooms in the damp Bavarian forests. Three other billionaire dynasties have managed to survive through Germany's 20th-century Sturm und Drang. None has thrived more spectacularly than the von Fincks' princely Bavarian neighbor, Johannes Batista deJesus Maria Miguel Friedrich Bonifazius Lamoral Furst Thurn und Taxis. An ancient and nimble aristocratic family, the Thurn und Taxis clan surfed through the tidal wave of Central European history. When the Napoleonic wars ended the family's centuries-old monopoly as postmasters of the Hapsburg Empire, they snapped up thousands of acres of land expropriated from the Catholic Church. Included was a 500-room castle in Regensburg that the family still uses. During Germany's 19th-century industrial boom, the family widened its commercial holdings and founded a private bank. The blue-blooded Thurn und Taxis steered clear of Hitler's Reich. Though they lost thousands of acres of land in Bohemia when the Communists took power, they retained control of some 100,000 acres in West Germany. The sole heir of this patrimony, Johannes, 61, is today Europe's largest landowner. But Johnny TNT -- a nickname that sticks from his raffish youth -- has evolved into an astute investor, adding some 175,000 acres of land in Brazil and Canada to his vast German holdings. In 1980 he married a penniless countess named Maria Gloria Schoenburg-Glauchau. No demure debutante, Gloria, known inevitably as Princess TNT, once created big headlines when she was arrested for allegedly smuggling hashish into Munich airport. No charges were brought. Since their marriage, the couple seems settled if not quite tamed. He and Gloria have produced three children. Among German manufacturers who did hook their star to the fallen Nazis, none have rebounded higher than the Flick family. For his prominent role as a weapons builder during Hitler's rearming of Germany, industrialist Friedrich Flick was sentenced to a seven-year prison term (of which he served three years) by the Nuremberg court and was forced to sell his coal and iron holdings. As punishments go, Flick's turned out just fine. He invested the cash proceeds in Daimler-Benz (becoming the luxury carmaker's largest shareholder), a Cologne insurance company, and several manufacturing companies. All prospered, and on his death in 1972, old man Flick left an estate worth $1 billion to his youngest son and namesake, Friedrich Karl Jr., 60. Once more playboy than businessman, Freddy sold his industrial holdings in 1985 for $2.8 billion, but he retains a stake in the insurance company and is the largest single shareholder of Deutsche Bank, Germany's largest commercial bank. Germany's postwar boom also lifted the Quandt family into the stratosphere of the super-rich. Herbert Quandt, who was left at war's end with stacks of nearly worthless shares inherited from his investor father, patiently waited for German industry to revive, converting his appreciating paper into a 70% stake of once-struggling carmaker BMW. Since Herbert's death in 1972, the estate of his widow, Johanna, and his five children has soared to $2.8 billion. West Germany's spectacular postwar economic success has created a lot of new millionaires, but just two families have cracked the billion barrier. After the war Karl Albrecht, 67, and his brother Theo, 65, came home to help their widowed mother run a delicatessen in Essen. They cashed in on the pfennig- pinching habits of German Hausfrauen by building a chain of no-frills deep- discount stores they called ALDI, short for Albrecht Discount. Today their 1,800-store empire stretches from the North Sea to the Alps, creating an Albrecht family fortune worth $1.1 billion. West Germany's other postwar billionaire is Reinhard Mohn, 66. Captured by Allied troops while fighting with Rommel's forces in Tunisia, Mohn was sent to a prison camp in the U.S. To pass the time and perfect his English, he read every Book of the Month Club release. Returning to the dreary north German city of Gutersloh in 1947, he took over the small Bertelsmann Bible-publishing house that belonged to his mother's family. He expanded the business to $ include general-interest books. Setting up his own monthly book club, he sent squads of salesmen door to door to sign up subscribers. Mohn expanded his book clubs throughout Europe and Latin America, and as the clubs prospered, he diversified into magazine publishing, records, and television and film production. Last year Bertelsmann bought U.S. book publisher Doubleday and RCA records to surpass CBS as the world's largest media conglomerate. Mohn, who controls 90% of Bertelsmann's shares, has a net worth of $1.7 billion. Mohn created a foundation to administer his holdings after his death, but his three children will not enjoy the full benefit of their father's riches. With West Germany's high inheritance taxes, the job of preserving a wealth of billions is still no mean feat. But it's a sure sight easier for the heirs of the German billionaires today -- not to mention for the rest of the world -- than in the bad old days.