„War is an equation with many unknowns; and this already refutes the thesis of invincibility. History does not know invincible armies.“
The wars of the past show us that even armies that had won brilliant victories for decades, in some cases were not only defeated but even disintegrated and ceased to exist. Such a fate, for example, befell the army of Napoleon, who for almost two decades kept the whole Europe under its boots. The army needs to instill a spirit of confidence in its power, but not in terms of boasting. Bragging about invincibility brings harm to the army.
Speech to Red Army personnel, 13 May 1940