Two women on coastlines 3,000 miles apart have joined forces to examine the mystery of the early 20th century exodus of black families from Gwynn’s Island in Mathews.

Maria Montgomery of Norfolk is the great-granddaughter of James Henry Smith, a black Gwynn’s Island resident who, on Christmas Eve in 1915, was accused of assault of a white man and found guilty by a jury. Montgomery said she believes this episode initiated the exit of black residents from the island.

GWYNN’S ISLAND PROJECT IMAGEJames Henry Smith is at the center of the mystery of the exodus of Gwynn’s Island’s black families in the early 20th century.

Allison Thomas of Los Angeles is the great-great-great-granddaughter of Mary T. Edwards of Gwynn’s Island, whose diary lists “people seized as contraband by the Union Navy in 1863,” among them James Henry Smith’s parents, William M. “Billy” Smith and Dolly Jones.

Montgomery found Thomas in 2016 through their linked family tree on Ancestry.com. She asked Thomas ...