

Approaching the matter from the standpoint of the proletariat and the proletarian revolution, Engels, like Marx, upheld democratic centralism, the republic–one and indivisible. He regarded the federal republic either as an exception and a hindrance to development, or as a transition from a monarchy to a centralized republic, as a “step forward” under certain special conditions. And among these special conditions, he puts the national question to the fore.
Although mercilessly criticizing the reactionary nature of small states, and the screening of this by the national question in certain concrete cases, Engels, like Marx, never betrayed the slightest desire to brush aside the national question
Engels proposes the following words for the self-government clause in the programme: “Complete selfgovernment for the provinces [gubernias or regions], districts and communes through officials elected by universal suffrage. The abolition of all local and provincial authorities appointed by the state.”
It is extremely important to note that Engels, armed with facts, disproved by a most precise example the prejudice which is very widespread, particularly among pettybourgeois democrats, that a federal republic necessarily means a greater amount of freedom than a centralized republic. This is wrong. It is disproved by the facts cited by Engels regarding the centralized French Republic of 792-98 and the federal Swiss Republic. The really democratic centralized republic gave more freedom that the federal republic. In other words, the greatest amount of local, regional, and other freedom known in history was accorded by a centralized and not a federal republic.
V. Lenin - State and Revolution
V. Lenin - “Left-Wing” Communism