PARIS, Oct. 21 (Xinhua) -- France mourned Samuel Paty, a teacher decapitated in a terrorist attack last Friday, with a national ceremony led by President Emmanuel Macron on Wednesday evening.

The memorial service was held at Paris' Sorbonne University with the attendance of 400 people, including Paty's family and colleagues, government officials, and the country's main political figures.

The coffin of Paty, who was posthumously awarded "Legion d'Honneur," or the Legion of Honor in English, the highest French order of merit for military and civil merits, was carried by republican guards into the courtyard of the university.

Paty "was killed because he embodied the Republic which is reborn every day in the classrooms, the freedom which is transmitted there," Macron told the gathering.

"He was killed because the Islamists want our future. They know that with quiet heroes like him, they'll never get it," he said.

Last Friday, the 47-year-old history-geography teacher was beheaded near a college in Conflans-Sainte-Honorin, northwest Paris, by an 18-year-old refugee of Chechen origin.

The attacker, shot dead by police, had claimed responsibility for the assault in a Twitter post to retaliate the teacher's use of the Prophet Muhammad's cartoons in class.

Investigations revealed that Paty was subject of an online hate campaign after showing cartoons of Prophet Mohammad as part of a discussion on freedom of expression in early October. A parent of one student launched a call to "join force to say stop" in a Facebook video.

The attacker and the parent had exchanged a number of text messages prior to the assault, confirming a "direct causal link" between the parent's campaign and the death of Paty, anti-terror prosecutor Jean-Francois Ricard said early Wednesday.

Two minors aged 14 and 15 were among seven people brought before judge as part of the probe. They reportedly received cash from the attacker to identify the victim, added the prosecutor.

In January 2015, a mass shooting hit the offices in central Paris of satirical weekly magazine Charlie Hebdo, which published controversial cartoons including those of Prophet Mohammad. Twelve people were killed, including eight of the magazine's staff.