It was also significant because it was the first major battle of the Civil War fought on Maryland soil.

"In 1989, we formed the Central Maryland Heritage League, a nonprofit land trust, for the preservation of South Mountain, and Michael volunteered legal help so we were able to buy several parcels of land including Wise's Field, which was a key part of where the ... battle was fought," said George F. Bringham Jr., a Middletown carpenter who was president of the organization.

"We were flabbergasted that an attorney from Baltimore wanted to help us," said Mr. Bringham. "He'd drive an hour and a half after finishing work — he wouldn't even go home — and then at 9 p.m. or 10 p.m., he'd drive back home. Not only did he do free legal help, he also made contributions."

The group's efforts resulted in the establishment of South Mountain State Park.

"Without his help, it would not have become a state battlefield. He helped bring awareness to what we were trying to do," said Mr. Bringham. "He was the kind of person who'd give the shirt off his back to help someone out."

Mr. Bringham also pointed out that Mr. Rinn's birthday on Sept. 14 was the same day of the Battle of South Mountain.

In his walks across battlefields, Mr. Rinn picked up bullets that had laid undisturbed, even after the passage of nearly 150 years.

"He had cases and cases of them which he displayed," said his wife of 36 years, the former Jacqueline "Jackie" Denhard. "He had other Civil War artifacts and an extensive library on the war."

In addition to reading, Mr. Rinn enjoyed traveling and went to Ireland to celebrate both his 60th birthday and his Irish heritage, where he "danced every dance with his wife," said family members.

Mr. Rinn was a communicant of St. Joseph Roman Catholic Church, 103 Church Lane, Cockeysville, where a Mass of Christian burial will be celebrated at noon Wednesday.

In addition to his wife, Mr. Rinn is survived by a son, Christopher M. Rinn of Cockeysville; a daughter, Megan C. Fitez of Sparks; three sisters, Mary Beth Smolev of Baltimore, Trish Rinn of Easton, and Margaret Dietz of Pittsburgh; and a granddaughter.