Amelia Boynton Robinson, who was called the matriarch of the voting rights movement — and whose photograph, showing her beaten, gassed and left for dead in the epochal civil rights march known as Bloody Sunday, appeared in newspapers and magazines round the world in 1965 — died on Wednesday in Montgomery, Ala. She was 104.

Her death was confirmed by Shawn Eckles, a family spokesman.

Mrs. Boynton Robinson was one of the organizers of the march, the first of three attempts by demonstrators in March 1965 to walk the 54 miles from Selma, Ala., to the capital, Montgomery, to demand the right to register to vote.

As shown in “Selma,” the Oscar-nominated 2014 film directed by Ava DuVernay, Mrs. Boynton Robinson (played by Lorraine Toussaint) had helped persuade the Rev. Dr. Martin Luther King Jr., who would lead the second and third marches, to concentrate his efforts in that city.

Bloody Sunday took place on March 7, 1965. As they tried to cross the Edmund Pettus Bridge in Selma, some 600 black demonstrators, led by John Lewis and the Rev. Hosea Williams, were set upon by Alabama state troopers armed with tear gas, billy clubs and whips.