[2] He entered the studio of Thomas Ball of Charlestown in his early teens and stayed until the mid-1860s.

His first sculptures seem to have been cabinet-size busts of Henry Wadsworth Longfellow (New Hampshire Historical Society, Concord) and Charles Sumner, both modeled from life around 1863.

[3] By his 20th birthday, Milmore received a commission for three giant figures ("Ceres", "Flora" and "Pomona") for the front of the Horticultural Hall in Boston; the restored versions are now on display at the Elm Bank Horticulture Center.

He subsequently designed the Roxbury Soldiers' Monument at Forest Hills Cemetery in Jamaica Plain, Massachusetts (1867), the American Sphinx in Mount Auburn Cemetery (1872), the Statue of John Glover on Commonwealth Avenue (1875), the Soldiers and Sailors Monument for the Boston Common (1877), and a bust of Senator Charles Sumner, now displayed in the United States Senate.

[4] Daniel Chester French created a memorial tribute entitled Death and the Sculptor for the grave of Milmore and his brother in Forest Hills Cemetery.