The Georgia Democrat, an iconic civil rights leader from his activism in the 1960s, recalled how around 600 marchers planned to walk from Selma to Montgomery to promote voting rights, and were met with violence by police.
The marchers in 1965 also sought to protest the death of Jimmie Lee Jackson, a man who had been killed a month earlier by a state trooper during a separate march to promote black voter registration. They only made it to the Edmund Pettus Bridge
before getting attacked by state and local law enforcement with clubs, bullwhips and tear gas -- hence the name "Bloody Sunday."
Lewis, one of those marchers, recalled the episode in a series of tweets.
"51 years ago, we said a prayer before setting out from Brown Chapel to march across the Edmund Pettus Bridge" Lewis tweeted.
In a tense standoff between marchers and law enforcement at the Edmund Pettus Bridge, neither side seemed to be backing down, according to Lewis.
"Down below, we saw a sea of blue...Alabama State Troopers putting their gas masks on" Lewis wrote.
"I was hit in the head by a State Trooper. I thought I saw death. I thought I was going to die" Lewis wrote.
Two days later, Martin Luther King, Jr. organized a symbolic march, but this time with court protection. That same night, three white ministers who supported the march were attacked by segregationist. One of those ministers, James J. Reeb, was killed.
"I had a concussion there at the bridge, and I've never been able to recall how any of us made it back alive" Lewis recalls.
From March 21, 1965 to March 25, over 25,000 marchers joined to finish the 12-mile walk from Selma to Alabama's capital of Montgomery. Five months later, Lyndon B. Johnson signed the Voting Rights Act.
The 2016 Democratic presidential candidates each referenced the anniversary on Twitter. That as both are aiming to address issues of importance to many black voters, including concerns over police brutality, high incarceration rates and economic inequality.
Font-runner Hillary Clinton wrote: "Bloody Sunday, March 7, 1965, was a day of horror and pain. But it was also a day of resilience and grace."
Vermont Sen. Bernie Sanders, tweeted: "The people who risked their lives in Selma showed that when people stand together for justice nothing is impossible."