French words in English
There have been French words in English since the time of Chaucer. It was he who imported those that end in -sion or -tion (though he often also spelt them -cion or -cioun). More recent additions are ménû, machìne (-sh-), façàde (*fəssàd), crèpe and elìte (the accents, which are not the same as the ones used in French, show stress and pronunciation, see English phonemes for the IPA and English spellings for a table). English more-or-less French pronunciation is typified by the proper names *Cítron, *Përzho and *Rénno for Cítroen, Pëugeot and Rénault. Pronouncing French words too Frenchly sounds pretentious in an English context. Why say 'Stephàne Grapellỳ' when it is so much easier to say *Stéfən Grəpélly? Boulŏgne (*Bə-lŏin, as opposed to French 'Bû-lónyə') and Páris (with s sounded) have anglicised pronunciations, as do the painters Dègàs (*Dâygà for 'Dəgá' - the name was originally de Gas) and Rénoir (*Rénwà instead of *Rənwàr - the anglicised pronunciations are generally spurned by those anglophones who have learnt French, but even they would not normally in an English context pronounce the final r in Renoir); by contrast the more recently famous country Nigèr has a French-style pronunciation, *Nì-zhãir - in contrast to Nigêria (*Nîjêria) and the river Nîger.
But many more French words and phrases are less assimilated than those above, and they are often written, like other foreign words, in italics. They can retain their written French accents in (especially British) English. None of these accents should be regarded as compulsory in English, but they are often used (as are also the cedilla in curaçao, probably from Portuguese, and the umlaut in the German doppelgänger).