John Donald MacArthur (1897-1978) was one of the three wealthiest men in America at the time of his death, and was sole owner of the nation’s largest privately held insurance company.

One of seven children, Mr. MacArthur was born in an impoverished coal-producing area of eastern Pennsylvania. His three brothers who survived childhood all achieved success in their fields: Alfred in insurance, Telfer in publishing, and Charles as a newsman, playwright, and Hollywood screen writer. John held several jobs, including stints as a newspaper reporter, as an insurance salesman in his brother’s company, and in three unsuccessful business ventures, before turning to insurance as his life’s work.

In 1928, at the age of 30, Mr. MacArthur bought the Marquette Life Insurance Company, and in 1935, he borrowed $2,500 to acquire the financially impaired Bankers Life and Casualty Company of Chicago. Five years later, Bankers had more than $1 million of assets; by 1977, they had surpassed $1 billion. At his death, Mr. MacArthur’s insurance companies had more than 3 million policyholders, with $5.5 billion of insurance in force, and a sales staff of more than 5,000 agents and brokers.

In the 1960’s, Mr. MacArthur’s attention turned to real estate and development. He conducted his business at a table in the coffee shop of the Colonnades Beach Hotel, in Palm Beach Shores, Florida. He owned the hotel, and he and his wife lived in a modest apartment overlooking a parking lot.

At one time or another, Mr. MacArthur’s holdings included 100,000 acres of land in Florida, primarily in the Palm Beach and Sarasota areas; several development companies and shopping centers; paper and pulp companies; 19 commercial, office, and apartment buildings in New York City; several publishing enterprises; hotels; radio and television stations; banks and 12 insurance companies.