Marx didn't really say what form his "dictatorship of the proletariat" would take, what it would look like or how the proletariat are supposed to maintain control of a state. Most of his 20th followers took the term to mean the rule of their party.
> Marx argued for a working *class* capture of state power, just
> like you say here:
>
>
>>Establishing a state controlled by the proletariat, as advocated by the
>> Manifesto, is not possible and attempts to do so leads to the
>>formation of a new group of exploiters to replace the old ones.
>
>
> Has there ever been a working *class* capture of political power?
No, the workers have never seized state power because such a thing is not possible. A "proletarian state" is like a square circle; it doesn't exist. You could call something a square circle, but that doesn't mean it exists.
> Or has
> there been a capture of power on their behalf by a vanguard party, as
> advocated by Lenin but not Marx.
The seizure of state power by a minority is the logical outcome of an attempt to establish a worker's state since the state is an organ for the domination of the majority by a minority.
Joe