The Charlie Hebdo attack, which was followed by the murder of a police officer and a siege in a Jewish supermarket, aroused a wave of sympathy in France and around the world.
Millions of people responded to the government's call to show solidarity with the victims on the following Sunday and the slogan "Je suis Charlie" (I am Charlie) appeared on demonstrations, walls and social media across the globe.
Wreaths were laid at the sites of both massacres and media and politicians declared their determination to defend "republican values", most importantly freedom of expression, and "defeat terrorism".
But controversy soon followed the solidarity.
In France comedian Dieudonné added a conviction for "condoning terrorism" to his string of sentences for anti-Semitism for tweeting that he felt "like Charlie Coulibaly" - combining Charlie Hebdo with supermarket killer Amédy Coulibaly in one name - after being told he was unwelcome on the solidarity protest.
That and several other convictions on the same charge gave rise to charges that freedom of expression does have limits in France.
While its sales soared, the paper was accused of flirting with Islamophobia by liberal commentators in some English-speaking countries.
When a few months later historian and sociologist Emmanuel Todd said that the solidarity marchers' "latent values" were the expression of "social power" and "domination", Prime Minister Manuel Valls was so furious he published a response in Le Monde newspaper, accusing him of "imposture" and expressing an "ambient cynicism" championed by "intellectuals who no longer believe in France".
Valls appeared more open to the argument that something must be done about the alienation felt on France's impoverished housing estates, many of whose residents are of immigrant origin, a small minority tempted by radical Islamism.
Shortly after the attacks he told the media that a "territorial, social and ethnic apartheid" exists in France, prompting criticism from mainstream right-wing leader Nicolas Sarkozy and Florian Philippot of the far-right Front National.
Although he refused to back down on his terminology, the declaration did not lead to any noticeable change to the government's social policy, its argument being that the key task was to create jobs, which its economic policies have so far failed to do.
The attacks did nothing to make life easier for France's Muslim population, a result that was perhaps intended by the Islamic State (IS) armed group, which claimed responsibility for them.
Islamophobic attacks tripled to 400 in the first three months of the year, according to a government-appointed anti-racism commission, which reported even more anti-Semitic acts, 850 reported to police during the course of the year.
Politicians responded to the attacks with declarations of national unity and calls for tighter security.
The former did not last long but the latter was swiftly delivered, even if not to the total satisfaction of the right-wing opposition.
The government flooded the streets of Paris and other cities with 10,500 troops, posted outside media houses, synagogues and other sites judged senstive, along with 5,000 extra police.
The secret services were also urged on to extra efforts, with questions raised as to why they had not spotted the killers, who were already known to police, and prevented the massacre.
A number of terror plots have been foiled since, according to the government.
But not all of them - three police officers were attacked by a knife-wielding man in Nice in February, a man decapitated his boss and tried to blow up a factory in the Rhône valley in June and four American tourists prevented a man opening fire on a train travelling from Amsterdam to Paris in August.
Most shocking of all were the 13 November Paris attacks on a rock concert and several bars and restaurants.
Some 130 people were killed and hundreds injured but the response was more low key - no massive march but individuals placing flowers at the scenes of the carnage, more efforts to distinguish the majority of Muslims from the actual and aspiring terrorists and more insistent questioning as to how young men born in France and known to the security services managed to launch a massacre in central Paris.
President François Hollande declared that the country was at war with terrorism and the government's response was to beef up state powers again, declaring, then prolonging, a state of emergency and controls reinstated at France's borders.
Within a fortnight nearly 2,000 premises had been searched, over 300 people had been placed under house arrest, over 200 people had been detained after raids and 293 weapons had been seized, Valls announced.
Not all of those confined to their homes were suspected of jihadist tendencies.
Green and hard-left MPs protested that ecologists, whom the authorities claimed had been associated with violent environmental protests in the past, were placed under house arrest while the Cop21 climate change talks took place in Paris.
There was even more uproar on the left over the government's plans to change the constitution to add a provision for stripping people with double nationality convicted on terror charges of their French citizenship.
Critics claimed the move was a breach of the principle of equality of all French nationals, creating an extra punishment for one class of citizen, and, anyway, unlikely to deter would-be suicide bombers.
Valls accused them of forgetting the country was at war and that French citizenship was conditional on accepting republican values.
The attacks also had an effect on foreign policy.
As Islamic State became a magnet for radicalised young people - 930 French nationals or residents were fighting in its ranks in September, according to Interior Minister Bernard Cazeneuve - the French authorities tried to clamp down on jihadist networks and then joined the US-led coalition in bombing Syria, reversing a previous decision to only do so in Iraq.
IS cited the air strikes as one of the reasons for the 13 November attacks.
On the anniversary of the Charlie Hebdo attacks Hollande paid tribute to the police officers killed and promised "firmness", "reactivity" and "unity".
Within minutes of his speech a man was shot dead trying to attack a police station with a cleaver, dressed in a fake suicide vest.