In 1883, Portner bought Mathis' estate in Manassas, Virginia, Virginia. When they had visited in the past, Portner's wife had said that the land, with its view of the Bull Run Mountains, reminded her of her homeland in Switzerland, and that she loved it. As time went on, Portner purchased more and more surrounding farmland, growing his estate to nearly 2,200 acres. Comprising primarily the Weir family's Liberia estate and Wilmer McLean's famed Yorkshire estate, Annaburg would encompass a large portion of the Civil War battlefield, historic mansions, and several earthwork Fortifications including Fort Beauregard. Portner managed to turn miles of battle-scarred earth and scraggly cornfields into lush pastures for his stock and horse farms, successfully establish a dairy farm at Liberia, and considerably expand Mathis' original orchards and vineyards. He partnered with Washington, D.C. winemaker Christian Xander to produce wine from his grapes, which won a gold medal at the Paris Exposition of 1900. Annaburg also featured a 300-acre fenced in deer park where Portner often held deer and quail hunting parties.