Accord of past participle

Question

"La devise a ensuite disparu pendant la majorité du XIXe siècle." Why does the preceding sentence say "disparu" and not "disparue"?

Accepted Answer

La devise is the subject - compound verbs with auxiliary avoir are invariable and do not “show agreement” unless the direct object of the verb precedes it.
special-cases-when-the-past-participle-agrees-in-number-and-gender-when-used-with-avoir-in-le-passe-compose-conversational-past

Answer

Hi James,
The verb 'disparaître' is conjugated with avoir although it is intransitive and doesn't have an object.
Take a look at the following lesson with applies to disparaître too.
Conjugate paraître, connaître and derivatives (+ avoir) - except apparaître and naître - in Le Passé Composé (conversational past)
The only agreement of the past participle with the subject is with those verbs which are conjugated with 'être'.
Hope this helps!