I don't know of any person called Engles who would be significant in this context, so I can't tell you if there is one you should know about. The Engels who said what you quoted above, also said - literally in the sentence preceding your quote:

Why do the anti-authoritarians not confine themselves to crying out against political authority, the state? All Socialists are agreed that the political state, and with it political authority, will disappear as a result of the coming social revolution, that is, that public functions will lose their political character and will be transformed into the simple administrative functions of watching over the true interests of society.

As always, context matters. And I'll trust the context created by the words and interpretations of respected historians way more than I'll trust some randos on Lemmy who only excel at selective quoting.

[–] Objection@lemmy.ml 8 points 3 days ago* (last edited 3 days ago)

Right, and the part you quoted is in the context of what immediately followed. The clarification that he was talking about the eventual ideal, and that in the meantime, using authoritarian measures were necessary to the point that anyone who opposed them was supporting reactionaries.

It should of course be noted that Marx expected a spontaneous, worldwide revolution, starting from the most developed countries. This was something that he got completely wrong, (he was not a prophet) and the socialists who put his ideas into practice had to adapt to the real circumstances that they found themselves in. In the case of a worldwide revolution, of course it would be easier to persue the phasing out of authoritarian measures sooner, since they wouldn't be necessary to protect against foreign threats and subversion (something presumably included in the not-yet-destroyed "social conditions that gave birth to the political state"). Even in such a scenario, Engles was extremely clear that he considered such measures absolutely necessary.

What "respected historians" are you referencing? I haven't seen you cite any. Care to share with the class?