A stylistic variation, relative to Philippa's suggestion. I prefer the more succinct (2 words instead of 5) and closer-to-the-French "purposeful obscurity." For the same reason, "only" instead of "nothing more."

An order of transfer from an altar-table, sent by a head of government had never explained what was requested. To seek intervention from a higher authority, the pressure placed on Vichy had taken the form of an ultimatum without calling, as a doctor could wait with a noted result. It was asked why the only thing from the darkness was the abstract authority and a prominent figure from the French state.

--------------------------------------------------
Note added at 2 days 19 hrs (2021-11-09 18:43:49 GMT)
--------------------------------------------------

'Un ordre de cessation était d'un retable, envoyé d'un chef de gouvernement n'avait jamais expliqué ce qu'ils avaient demandé. Pour chercher de l'intervention d'une autorité plus haute, la pression mise sur lui avait pris la forme d'un ultimatum, sans appeler, comme un médecin attendrait avec un résultat noté. On avait demandé pourquoi des ténèbres il n'y avait qu'une autorité abstraite de quelqu'un d'une importance de l'étât français.'

--------------------------------------------------
Note added at 6 days (2021-11-13 22:09:00 GMT) Post-grading
--------------------------------------------------

In the ST, "an order (to transfer)" is placed as the subject of the opening sentence, with a head of government in the subordinate clause, even though he was the one who'd issued the order. The ST following sentence is in the passive ('it was never explained who had requested it' OR 'no-one told who'd requested it'). As the ST continues, the subject becomes "'the pressure', which was placed over him had taken the form of an ultimatum ... " In the final part 'the darkness' or 'the shadows' becomes the subject from which an abstract authority was released, with 'a prominent figure from the French state' as an object in a subsequent subordinate clause.
Hopefully that explains my unusual suggestion in English, which is an attempt to equal an evasive use of language with a passively non-accusatory voice throughout.

--------------------------------------------------
Note added at 6 days (2021-11-13 22:10:30 GMT) Post-grading
--------------------------------------------------

"un ordre de cession" est la bonne phrase au lieu d"'un ordre de cessation".

--------------------------------------------------
Note added at 16 days (2021-11-23 22:25:22 GMT) Post-grading
--------------------------------------------------

C'était d'un ordre de cession (d'un transfer) d'un retable (une table particulière d'une église, sur laquelle il y a des cérémonies réligieuses).

--------------------------------------------------
Note added at 18 days (2021-11-25 13:33:41 GMT) Post-grading
--------------------------------------------------

C'est constaté qu'il y a avait de 'la pression qui s'excerça sur Vichy ..' d'une voix passive, sans expliquer ni accuser qui avait excercé cette pression-là sur lui.
L'auteur du texte a usé le temps du passé simple (le passé historique) avec les verbes 'fut' et 'excerça' en dénotant que les évennements ont eu lieu il y a longtemps, au passé distant, aux actions complétées.