Sgt. Yevgeniy Ryndych, 24, died Wednesday in Ramadi, the Defense Department said.
His family and fiancée were told on the same day she got a package with the engagement ring, said the soldier's brother, Ivan Ryndych.
"He had proposed over the phone from Iraq within the past month," said Ivan Ryndych, 20. "He bought an engagement ring over the Internet."
Ryndych, who was born in Ukraine and immigrated to New York City as a teenager, was on his second tour of duty in Iraq, his brother said. He was assigned to the 1st Battalion, 9th Infantry Regiment, 2nd Brigade Combat Team, based at Fort Carson, Colo.
Ivan Ryndych said his brother had gone on to a special-forces unit after his first tour in Iraq ended last year. But then he volunteered to rejoin his old unit when it headed back to Iraq, his brother said.
"His exact words to me were, 'I don't want to leave them behind,' " Ivan Ryndych said.
Ivan Ryndych responded angrily when he realized he lost his brother on the same day a report criticizing President Bush's failing Iraq strategy came out.
"It won't change anything," Ivan Ryndych told the New York Daily News.
In an interview with Newsday, Ivan Ryndych said that until his brother's death, he had also contemplated a career in the Army. "I changed my mind," he said. "I just don't want to put my parents through the same thing."
The family immigrated to Brooklyn from Ukraine in 1998 and has since moved to Staten Island. A flag flew at half-staff outside their home Thursday; inside, the living room displayed photographs of Ryndych in uniform.
Ryndych graduated from Lafayette High School in Brooklyn, according to published reports.
A voracious reader who enjoyed military-strategy games, he had wanted to join the Army for years, his brother said.
"He just liked the whole Army concept," Ivan Ryndych said.