Miljenko “Mike” Grgich, a celebrated winemaker who helped establish Napa Valley as one of the world’s premier wine-making regions, has died. He was 100.

Grgich died in his sleep Wednesday morning at his home in Calistoga, California, according to his winery, Grgich Hills Estate.

Grgich was born on April 1, 1923, in Desne, Croatia. His father was a winemaker, and one of his earliest memories was stomping on the grapes at harvest time. At the age of 10, he left his village to live with his sister and further his schooling. His father’s parting words to him became his life’s mantra: “Every day do your best, learn something new and make a new friend.”

Grgich studied enology and viticulture at the University of Zagreb, but as communism gripped Croatia, he searched for a way out. In a whispered conversation with a professor, he learned of a place called “California” and made plans to go there through an exchange program in Germany.

Grgich left Croatia in 1954 with a few U.S. dollars hidden in his shoe and a suitcase full of wine-making books. That suitcase, along with his trademark beret and a bottle of chardonnay, are now housed at the Smithsonian Institution in Washington.

Grgich won asylum in Canada after agreeing to work as a lumberjack in British Columbia. Finally, in 1958, he got a job offer from Lee Stewart, the founder of Chateau Souverain in Napa, California. He worked for several other wineries before joining Chateau Montelena in 1972.

In 1976, Grgich’s 1973 vintage Chateau Montelena chardonnay shocked the wine world, winning first place in a blind tasting in Paris. A cabernet sauvignon from Stag’s Leap Wine Cellars in Napa was also the top red wine at the competition.

“Mike’s impact on Napa Valley’s history and the world of wine cannot be overstated,” Napa Valley Vintners, a trade group, said Thursday in a statement. “We join the rest of our winemaking community in tipping our beret towards Mike Grgich and the legacy he will continue to have on wine.”

Chateau Montelena also paid tribute to Grgich Thursday.

“Mike played an integral role at the start of Chateau Montelena’s modern history as our first winemaker and will always have a special place in our hearts,” the winery said in a statement.

Grgich parlayed that success into opening his own winery — now Grgich Hills Estate — in 1977. He also played a pivotal role in rebuilding Croatia’s wine industry after the fall of communism. He opened Grgic Vina, a winery on the Adriatic Sea just north of Dubrovnik, Croatia, in 1996, and he established an endowment at the University of Zagreb for students studying winemaking. Grgich was granted a degree from the university in 1989.

Grgich also worked closely with Roots of Peace, an organization dedicated to eradicating minefields and returning the land to agricultural uses. Roots of Peace presented Grgich with a lifetime achievement award in 2022.

Grgich ran Grgich Hills Estate until 2018, when he turned over leadership to his daughter, Violet Grgich, and his great nephew, winemaker Ivo Jeramaz. This year, he celebrated as the winery earned its regenerative organic certification.

Grgich credited his longevity to his friendships and a glass of wine each day. He was preceded in death by his ex-wife, Tatjana Grgich. He is survived by his daughter, great nephew and one grandchild.