The shadow of Charles de Gaulle looms over France’s past and may in ways as yet unknown color its future. The son of General de Gaulle, Philippe, died Tuesday night at the age of 102. The following morning Philippe’s son, Pierre, wrote on X, “Admiral de Gaulle, my father, passed away last night. Let us salute the memory of a formidable father and a great Frenchman, whose sense of duty was matched only by his elegance and modesty. Vision, honor and simplicity: that is ultimately Gaullism.”

Not necessarily an ideology, Gaullism is synonymous with a French way of thinking that is predicated on resistance — to the Nazis during World War II and after that,  to going the French way when it suits the national agenda. That goes a long way toward explaining why in 1966 President de Gaulle yanked France out of NATO’s integrated command. (It’s back, but it took a while.) 

It also explains the emerging fractures in French unity over aid to Ukraine. As it happens, the passing of Charles de Gaulle fils was preceded only by a few hours by a non-binding parliamentary vote on a bilateral security agreement between Paris and Kyiv. While a majority of French lawmakers supported it, the left-wing France Unbowed (LFI) party voted against it while the far-right National Rally, until recently headed by Marine Le Pen, abstained. 

This was a symbolic vote on a security cooperation agreement that Presidents Macron and Zelensky signed at the Elysée Palace last month. In the Fifth Republic, the French president wields most of the power as foreign policy is concerned — a tradition that arguably started with de Gaulle. What happened on Tuesday is of no immediate concern to Ukraine’s war effort, but it could spell trouble in the future because it shows that Mr. Macron’s unwavering support for Kyiv is not shared across the political spectrum.

The parties to the left and right of his ailing Renaissance party said that red lines were crossed making it impossible to back Mr. Macron’s policy of supporting Ukraine’s fight with a long-term military agreement. The agreement includes a strengthening of military cooperation between France and Ukraine for the next 10 years, notably in the realms of artillery and air defense.

Ahead of the vote, the prime minister, Gabriel Attal, told French lawmakers, “Despite all the rules and all the international conventions, we are at a decisive moment. Russia is a threat not only to Ukraine, but also directly to us, to Europe, to France and to the French people.” He added: “The message from the president of the Republic [is] very clear: we will not abandon Ukraine and we are not ruling out any option as a matter of principle.”

Paris has also promised to provide more than $3 billion to Kyiv in 2024.  The armed forces minister, Sébastien Lecornu, told the newspaper La Parisien on Monday, “Our security comes at a price.”

In an address to the National Assembly, Mr. Attal attempted to allay tensions caused by Mr. Macron’s recent remarks about the possibility of sending troops to Ukraine but also took a potshot at his political foes, who are gaining steam ahead of European parliamentary elections in June.

“We are working within a considered framework to reaffirm our support for Ukraine, but without waging war on Russia and rejecting any logic of escalation,” Mr Attal said, adding that voting against the accord with Kyiv would be the sign of a France that was “turning its back” on its history.  “To abstain is to flee,” he declared. 

Yet Ms. Le Pen, for one, was not buying the young Mr. Attal’s argument. “Either we are pro-Macron, or we are accused of being pro-Putin,” she replied in the Palais Bourbon, where the National Assembly assembles. “We have a duty to the French people: It is the lives of our young soldiers that will be at stake if, by some misfortune, Macron’s warlike announcements turn out to be implemented.”

Before casting his “no” vote,  France Unbowed’s Arnaud Le Gall asked, “Yes or no, do we accept that France, a nuclear power, should place itself in a situation of war with Russia, another nuclear power?”

Yet the resounding “no” also exposed fissures in the left. Another member of France Unbowed, François Ruffin, wrote before the vote that bringing Poland, Hungary, and Romania into the EU in the 2000s amounted to a “silent cataclysm” that caused “the destruction of a million industrial jobs” — and said that admitting Ukraine to the  bloc would be a similar mistake. 

Mr. Macron, for his part, is less perturbed by the protestations from the left than he is by the surging popularity of the right. He has often accused the National Rally of going too easy on the Kremlin. In tacit acknowledgement of that perception the new party president, Jordan Bardella, said that he could support the agreement “in principle” but that les lignes rouges — red lines — prevented him from doing so. 

Abstention from the vote was in some respects a canny maneuver by the National Rally to blunt any domestic criticism and preserve the momentum it has going to the EU elections in June. 

On Wednesday the debate on the security agreement will move to the French senate, where it will likely pass, but with similar reservations expressed by the leftist parties and National Rally. 

For Marine Le Pen, a bigger challenge is how to keep channeling the legacy of Gaullism ahead of French presidential elections in 2027. Outside of Paris, the French tend to be more skeptical of the EU and the erosion of national identity that invariably accompanies its expansion. The challenge is also a personal one: Ms. Le Pen ran against Emmanuel Macron twice already and lost both times. The difference now is that Mr. Macron can’t run again. She can.