The passé simple: for reading, not speaking
CEFR C1
Inversion after a fronted adverbInverting the subject after the adverbs that require it, adding the linking -t- where…Cleft sentences: c'est… qui, ce qui… c'estHighlighting an element with c'est… qui, c'est… que and the ce qui / ce que / ce dont…Connectors for formal argumentUsing the connectors that carry a French argumentative text, and telling them apart from…The imperfect subjunctive, for readingRecognising the forms when reading and knowing which spoken tense they match, without…The impersonal constructions of formal FrenchOpening the sentence with impersonal il and giving each phrase its preposition and mood.Accents and the cedillaPlacing é, è, ê and ç correctly, and knowing that in French an accent changes the sound…The rule, in three lines
The passé simple is the past tense of novels, tales and feature writing. Nobody speaks it: you learn it in order to recognise it when reading. The -er verbs make -a and -èrent; the irregulars have to be seen: il fut, elle vint, ils prirent.
The usual slip. Failing to recognise it and assuming it is an unknown verb. «Il vint» and «ils prirent» look nothing like their infinitives, so you end up hunting for a word that is not in the dictionary.
Why it catches you out. English has one simple past for both speech and writing, so there is nothing to map this onto. The upside is that the temptation to use it never appears; the difficulty is purely recognising it when reading.