PARIS—In targeting Abdelhamid Abaaoud in a raid, French authorities removed from Islamic State’s ranks a prominent figure who they said blended his battlefield experience in Syria with a network of associates in Europe to lead one of the bloodiest terror attacks in French history.

In Syria, the Belgian was a military commander, or “emir of war,” in eastern Deir Ezzour province, according to local activists and news reports, an unusually high rank for a fighter who hailed from Europe. Friends from his early life in Brussels, in the predominantly Muslim district of Molenbeek, recall a “nice guy” who played soccer.

In Paris, officials say the 28-year-old militant assembled a potent arsenal that he planned to deploy against multiple additional targets—including Paris’ La Defense business district—following the attacks that investigators say he coordinated against a stadium, concert hall and other locales, killing 129 people.

Its strength was on full display Wednesday in an hourslong resistance to a raid in search of him in the northern Paris suburb of Saint-Denis. On Thursday, the Paris prosecutor said Mr. Abaaoud had been killed in the action.

Mr. Abaaoud’s ease in allegedly shuttling between Europe’s cobblestoned capitals and the killing fields of Syria shows how Islamic State has evolved from a militia focused on building a caliphate to an international terror syndicate with the command-and-control capability to direct terror attacks on the West from its territory.