There are many examples of proven false flags. There’s even one involving the French government.
•In 1985, the French foreign intelligence services infiltrated and sank a Greenpeace ship and blamed it on terrorists. https://en.wikipedia.org/wiki/Sinking_of_the_Rainbow_Warrior
•After a long series of bomb threats, the two people arrested for making bomb threats to Jewish community centers were 1) An Israeli https://www.theguardian.com/us-news/2017/mar/23/israeli-police-arrest-man-over-bomb-threats-to-us-jewish-targets and 2) A journalist named Juan Thompson https://theintercept.com/2017/03/03/statement-on-the-arrest-of-former-intercept-reporter-juan-thompson/
•Operation Northwoods- A plan to create false flag acts of terrorism against US citizens in order to provoke support for a war against Cuba. http://abcnews.go.com/US/story?id=92662&page=1 (PDF of the actual document: https://nsarchive2.gwu.edu/news/20010430/northwoods.pdf)
•The Lavon affair of 1954. As part of the false flag operation, a group of Egyptian Jews were recruited by Israeli military intelligence to plant bombs inside Egyptian, American, and British-owned civilian targets, cinemas, libraries and American educational centers. https://en.wikipedia.org/wiki/Lavon_Affair
•"Russia's parliament has declared that Joseph Stalin ordered his secret police to execute 22,000 Polish army officers and civilians in 1940, in one of the greatest mass murders of the 20th century. Mikhail Gorbachev admitted in 1990 that the NKVD was to blame for the massacre, after a half-century of the Soviets blaming it on Nazi troops." https://www.theguardian.com/world/2010/nov/26/russian-parliament-guilt-katyn-massacre (http://archive.is/bqPVG)
•"The U.S. was thinking of flying U2 reconnaissance aircraft with fighter cover over Iraq, painted in U.N. colours," the memo says, attributing the idea to Mr. Bush. "If Saddam fired on them, he would be in breach." https://www.nytimes.com/2006/03/27/world/europe/bush-was-set-on-path-towar-british-memo-says.html (https://archive.fo/ZGgpI)
•On 4 April 1953, the CIA was ordered to undermine the government of Iran over a four-month period, as a precursor to overthrowing Prime Minister Mohammad Mosaddegh. One tactic used to undermine Mosaddegh was to carry out false flag attacks "on mosques and key public figures", to be blamed on Iranian communists loyal to the government. They were successful. https://en.wikipedia.org/wiki/False_flag#Project_TP-Ajax
•"Operation Embarrass, a plan to try to prevent Jews getting into Palestine in 1946-'48 using disinformation and propaganda but also explosive devices placed on ships." https://www.thedailybeast.com/mi6-attacked-jewish-refugee-ships-after-wwii (http://archive.is/MKALq)
•The Bay of Pigs Invasion https://en.wikipedia.org/wiki/Bay_of_Pigs_Invasion
•Newly discovered documents show how in 1957 Harold Macmillan and President Dwight Eisenhower approved a CIA-MI6 plan to stage fake border incidents as an excuse for an invasion by Syria's pro-western neighbours, and then to "eliminate" the most influential triumvirate in Damascus. https://www.theguardian.com/politics/2003/sep/27/uk.syria1
•"Japanese troops staged a bombing of their own railway by placing explosives near the train tracks." https://www.japantimes.co.jp/opinion/2016/09/17/commentary/memories-1931-mukden-incident-remain-divisive/ (http://archive.is/lBC0i)
•The Anti-Muslim bombings in Paris, Cannes and Nice were a series of three terror bombings carried out by anti-Muslim extremists in French cities in the 1970s and 1980s. The bombers posed as an extremist Zionist group, calling themselves the Masada Action and Defense Movement, and leaving anti-Islam leaflets bearing Stars of David at the scene of one of the 1988 bombings. The Zionist moniker ended up being a false flag and in 1989, 18 members of the neo-Nazi French and European Nationalist Party were arrested for the bombings, which had been intended to provoke tensions between Arabs and Jews in France. https://en.wikipedia.org/wiki/Anti-Muslim_bombings_in_Paris,_Cannes_and_Nice (http://archive.is/dZhQD)
•Operation Himmler was a 1939 false flag project planned by Nazi Germany to create the appearance of Polish aggression against Germany, which was subsequently used by the Nazis to justify the invasion of Poland. This included staging false attacks on themselves using innocent people or concentration camp prisoners. https://en.wikipedia.org/wiki/Operation_Himmler (http://archive.is/4PEB5)
This information above is courtesy MKULTRA_Escapee on Reddit.