Saul Lobe of the AFP caught one of the images that's likely to linger.

His photograph shows a man in regular guide genes and hoodie, cropped hair, and a goatee, striding through one of the capital's mosaiced hallways.

From a pole slung over his shoulder hangs the Confederate flag.

It's bigger than he is. The portraits hanging in the background make eerie

witnesses to this desecration. On the left is Vice President John C. Calhoun,

a staunch supporter of slavery, and one of the architects of the South's secession.

The House voted to remove the picture last July. To the right is Charles Sumner, leader of the radical Republicans, the most vocal anti-slavery force during the Civil War.

He tried to have memorials to old racists removed from the capital as far back as 1865. But he's more famous as the victim of, until

this week, the most notorious act of violence perpetrated in the Senate. In 1856, the Democrat Preston Brooks nearly beat Sumner to death for his abolitionist views.

Blows from Preston's gold-headed walking stick left him blinded and unconscious.

Sumner had tried to escape by cowering under his desk.

This week, congressmen crouched on the floor with gas masks.

Others peered over their seats to film the mayhem on their phones.

In 1856, the senators brandished pistols to try and stop the attack.

But even during the Civil War, the Confederate flag never actually made it inside the capital.

This is checks and balance.

I'm John Prado, the economist's US editor.

Each week we take one big theme shaping American politics

and explore it in depth.

Today. Today can Republicans recommit their party to democracy? President Trump stood on the capital steps of his inauguration and promised to stop this American carnage. Four years later a violent mob stormed the

Capitol building in an attempt to overturn his election defeat. The scenes

shook America and its place in the world.

...