Everything looked almost perfectly normal that Wednesday in Paris. People were chatting here and there, busy with their usual activities. Yet, as I walked home, a strange atmosphere overwhelmed what seemed to be a divided city, as though some were aware of something terrible and others were completely oblivious.

When I saw my mother in front of my building, almost too distracted to recognize me, I soon realized that something monumental had occurred. I looked at her and finally asked what was wrong. Two masked men had attacked the office of Charlie Hebdo and, in less than five minutes, killed the newspaper’s bedrock, including cartoonists and writers Wolinski, Charb and Cabu. This bloodshed was followed by the screams of the two assailants: “Allahu Akbar,” then, “We have avenged the Prophet Muhammad.”

After providing this brief explanation, my mother left the building, leaving me as unsettled as she was when I first saw her. This was how I first heard about the terrorist attack at the newspaper’s office.

Charlie Hebdo, the Prophet Muhammad — those things were obviously related but I couldn’t figure out exactly how. It then all came back to me. Charlie Hebdo was a satirical left-wing newspaper which had published caricatures of the Prophet Muhammad and other religious figures (including Catholics, Jews and Muslims).

Cherif and Said Kouachi, the men responsible for this terrible massacre, were French orphans, recently enrolled in Yemen’s jihadist camps. Last Wednesday, they attempted to destroy freedom of expression by killing 10 and injuring eight members of Charlie Hebdo, before killing two policemen. Those crimes were unfortunately only the first in a series of attacks.

On Thursday, another shooting took place in Montrouge, a Parisian suburb. Clarissa Jean Philippe, a young police intern, was killed by Amedy Coulibaly, a member of the extremist Islamic rebel group ISIS. He called BFM TV at 7:20 p.m. that same night to declare he was working along with the terrorists targeting Charlie Hebdo: “Eux Charlie Hebdo, moi les policiers,” (“Them, Charlie Hebdo, me, the policemen”). On Friday, Coulibaly held 17 people hostage at a Parisian kosher grocery store after killing four men (Yohan Cohen, Yoav Hattab, Philippe Braham and Francois Michel Saada).

Paris became a city of mourning and fear for those three days. The slogan “Je suis Charlie” (I am Charlie) spread quickly as a symbol of support for the victims. The events were extremely important as they represented a threefold attack: one against freedom of expression, one against the Jewish population and a third against the police. The scale of these killings makes it the most serious attack in France since 1961.

Following the attacks, President Francois Hollande, along with Prime Minister Manuel Valls, called for a march to defend freedom and fight against terrorism. Marches were held in Paris and the provinces. I left the same day the incredible marches took place and therefore watched them from my computer in New Haven on Sunday night.

Two things were particularly striking about this protest. First, in Paris’s march, 44 foreign leaders held hands in solidarity with the victims. This demonstrated the extent of international support, and included both Israeli Prime Minister Benjamin Netanyahu and Mahmoud Abbas, the leader of the Palestinian Authority. Second, I was amazed by the unprecedented mobilization of the French people in the streets. More than 1.5 million marched in Paris, and 2.7 million marched in the provinces. In some cities, such as Lyon, 25 percent of the population took to the streets. This was, without a doubt, the largest coordinated protest France has ever known.

The smiles and calm force of the protestors were an inspiration. People of all backgrounds and ages gathered together for the march. It was a victory of unity, in which protestors overcame hatred and anger. The march was indeed not a targeted protest against the people who committed the massacres in cold blood, but rather an expression of universal democratic values: liberty of expression, equality and fraternity. It will now remain important to keep those values alive when facing terrorism.

A slogan my father saw flying on the Republic Square perfectly captured the spirit of those three horrible days followed by the beautiful march: “Pas de liberté sans courage” (“No freedom without courage”).

The French mobilization was courageous, but we must not forget the necessity of international mobilization moving forward. Indeed, last week Boko Haram militants destroyed several villages in Nigeria, killing more than 2000. The faith and democratic values demonstrated in France need to be embraced universally.

Cordelia De Brosses is a junior in Calhoun College. Contact her at cordelia.debrosses@yale.edu.