A.G. Gaston, the millionaire black businessman who bailed the Rev. Martin Luther King Jr. out of a Birmingham jail in 1963 for fear the civil rights movement would fall into turmoil without him, died Jan. 19 at the age of 103.

It was while in jail that King wrote his "Letter From Birmingham City Jail," his explanation to fellow clergymen of why protests must continue.

Mr. Gaston, the grandson of a slave, built a fortune in insurance and banking that helped give him standing with some members of Birmingham's white power structure and allowed him to act as a go-between during the civil rights struggle in the 1960s.

Mr. Gaston used his wealth and connections within the white community when Birmingham was torn by racial violence.

"Businesspeople could call him, and he would talk to people for us," said David Vann, a lawyer working with the white community who later became mayor.

It was a difficult position for Mr. Gaston. Some in the black community considered him an Uncle Tom, and Mr. Gaston himself was torn. He was talking on the telephone to Vann when, looking out his office window, he saw police use dogs and fire hoses against young black demonstrators.

"When the hoses were turned on the children, he said, I can't talk to you anymore,' and he hung up," Vann recalled.

Mr. Gaston posted the $5,000 bail to free King from jail following his 1963 arrest for marching without a permit. King wanted to stay behind bars as a political statement, but Mr. Gaston feared for the movement without his leadership.

"He and Dr. King had the same goals," said Louis J. Willie, Mr. Gaston's longtime right-hand man who wrote the check for King's bond. "As a businessman, his point of view was one way. As a minister and leader, Dr. King had another point of view."

Mr. Gaston was born in Demopolis in the old plantation country of western Alabama, moved to Birmingham as a youth and never made it past 10th grade.

In 1923, he founded the Booker T. Washington Insurance Co. with $500 and began selling policies to black steelworkers. He also opened Citizens Federal Savings and Loan and a string of other companies that catered to blacks in the segregated city.

Mr. Gaston's holdings were estimated at more than $35 million before he sold the insurance company to its employees for $3.5 million, the value of its capital assets, in 1987.

He worked at the bank until six months ago, despite losing a leg and his sight in one eye to diabetes.

Mr. Gaston is survived by his wife, Minnie, and five grandchildren.