He never sought the limelight, but Dwayne O. Andreas was one of the leading farm industrialists of the 20th century with deep business, political and personal connections in Minnesota. He opened and expanded huge export markets for grain, especially soybeans, and grew Archer Daniels Midland from a struggling agricultural processing company to a world power in the food and feed industry.

Along the way, Andreas met and courted some of the most important national and world leaders of his time, including Fidel Castro and Mikhail Gorbachev. And he developed a deep and lasting friendship with Hubert H. Humphrey, who was godfather to Andreas’ son, Michael.

Andreas, born March 4, 1918, in Worthington, died Nov. 16. He was 98.

“He was a big part of the Humphrey legacy and they were together all the time,” said former Vice President Walter Mondale. “He was a brilliant businessman and the center of the soybean business that helped everybody.”

Andreas began his career at his family’s farm and elevator business near Lisbon, Iowa, helping mix feed that was sold to local cattlemen. The operation grew into the Honeymead Products Co. in the mid-1930s, and Andreas dropped out of Wheaton College to help it grow into one of the nation’s largest animal-feed manufacturers. The family sold the operations in 1945 to Cargill, where Andreas went to work for the next seven years as a vice president.

Andreas during that time met Humphrey, who was then the Minneapolis mayor, and the two formed a tight relationship. Humphrey became a mentor for Andreas and later introduced him to several world leaders.

Andreas contributed generously to Humphrey’s campaigns for the U.S. Senate and presidency. The Justice Department investigated Andreas four times during the 1970s, and in 1974 he was acquitted of federal charges of making an illegal $100,000 contribution to Humphrey’s 1968 presidential campaign.

For Andreas, 1947 was a big year. He and his brother, Lowell, bought a soybean plant in Mankato and turned it into the largest soybean oil processor in the world. He also married Dorothy Inez. The couple went on to raise a son and two daughters. Inez died in 2012.

The Mankato plant was bought by a larger company, St. Paul-based Farmers Union Grain Terminal Association, in 1960. The purchase enabled the brothers to start a banking company, which became National City Bank.

In 1966, the Archer and Daniels families asked Andreas and his brother to become minority shareholders and executives in their midsize farm products company. Andreas moved the Minneapolis headquarters to Decatur, Ill., in 1969 to be near the company’s largest soybean processing plants. He became CEO and was elected chairman in 1970, a position he held until 1997.

Under his leadership, ADM grew from 40 processing plants and about 3,000 employees in the Midwest to 274 processing plants with 23,000 workers around the world. Its soybean exports shot up from $1.5 billion to $7 billion.

“He used his deep understanding of global markets and extraordinary business acumen to support policies and programs that helped food reach people in resource-scarce regions,” said Juan Luciano, ADM’s current chairman and chief executive, in a statement. Andreas’ brother, Lowell, who died in 2009, was president of ADM for four years.

Andreas met world leaders and convinced them of the importance of food as ADM expanded its international markets. At home, he donated generously to candidates in both Democratic and Republican parties, and met with every president from Harry Truman to Bill Clinton. His contributions to the Nixon campaign in 1972 also came under federal scrutiny during the Watergate investigation.

Many of the political donations went to leaders who successfully established federal subsidies for the ethanol industry and aided the high-fructose corn syrup processing business. Today, ADM is based in Chicago and is a leading producer of soybean oil, ethanol, animal feed, cocoa, vitamin E and the corn syrup sweetener used in many beverages and other foods. Its sales totaled $67.7 billion in 2015.

Another federal investigation of ADM, in the 1990s, led to a $100 million fine in 1996 for global price-fixing of a livestock feed additive and other products. Andreas stepped down as chief executive in 1997, and as chairman in 1999. Three executives, including Andreas’ son Michael, were convicted in 1998 and sentenced to two years in prison.

In addition to Michael, Andreas is survived by daughters Terry Andreas and Sandra McMurtrie; nine grandchildren; and 23 great-grandchildren.

Services have been held. A celebration of his life will be held in Bal Harbour, Fla., in January.