Highly recommend reading this entire speech at some point if you have the time. Despite dealing with pragmatic, practical issues of the time, it is imo still very much applicable to today, especially in regards to China and the ultra-left criticism of China's path:

Retreat is a difficult matter, especially for revolutionaries who are accustomed to advance; especially when they have been accustomed to advance with enormous success for several years; especially if they are surrounded by revolutionaries in other countries who are longing for the time when they can launch an offensive. Seeing that we were retreating, several of them burst into tears in a disgraceful and childish manner, as was the case at the last extended Plenary Meeting of the Executive Committee of the Communist International. Moved by the best communist sentiments and communist aspirations, several of the comrades burst into tears because—oh horror!—the good Russian Communists were retreating. Perhaps it is now difficult for me to understand this West-European mentality, although I lived for quite a number of years in those marvellous democratic countries as an exile. Perhaps from their point of view this is such a difficult matter to understand that it is enough to make one weep. We, at any rate, have no time for sentiment. It was clear to us that because we had advanced so successfully for many years and had achieved so many extraordinary victories (and all this in a country that was in an appalling state of ruin and lacked the material resources!), to consolidate that advance, since we had-gained so much, it was absolutely essential for us to retreat. We could not hold all the positions we had captured in the first onslaught. On the other hand, it was because we had captured so much in the first onslaught, on the crest of the wave of enthusiasm displayed by the workers and peasants, that we had room enough to retreat a long distance, and can retreat still further now, without losing our main and fundamental positions. On the whole, the retreat was fairly orderly, although certain panic-stricken voices, among them that of the Workers’ Opposition (this was the tremendous harm it did!), caused losses in our ranks, caused a relaxation of discipline, and disturbed the proper order of retreat. The most dangerous thing during a retreat is panic. When a whole army (I speak in the figurative sense) is in retreat, it cannot have the same morale as when it is advancing. At every step you find a certain mood of depression. We even had poets who wrote that people were cold and starving in Moscow, that “everything before was bright and beautiful, but now trade and profiteering abound”. We have had quite a number of poetic effusions of this sort.

And this part was especially amusing to me:

The other day I read an article by Comrade Rakosi in No. 20 of The Communist International on a new book by Otto Bauer, from whom at one time we all learned, but who, like Kautsky, became a miserable petty bourgeois after the war. Bauer now writes: “There, they are now retreating to capitalism! We have always said that it was a bourgeois revolution.”

And the Mensheviks and Socialist-Revolutionaries, all of whom preach this sort of thing, are astonished when we declare that we shall shoot people for such things. They are amazed; but surely it is clear. When an army is in retreat a hundred times more discipline is required than when it is advancing, because during an advance everybody presses forward. If everybody started rushing back now, it would spell immediate and inevitable disaster.

The most important thing at such a moment is to retreat in good order, to fix the precise limits of the retreat, and not to give way to panic. And when a Menshevik says, “You are now retreating; I have been advocating retreat all the time, I agree with you, I am your man, let us retreat together,” we say in reply, “For the public manifestations of Menshevism our revolutionary courts must pass the death sentence, otherwise they are not our courts, but God knows what.”

He's arguably the best of the "Five Heads" (I hate that we over-focus on just those five but whatever).