The famous quotation from Henry IV Part II (Act III, Scene 1, since you ask) refers both to the difficulties a ruler faces that his subjects know nothing about and, more specifically, to the difficulties a usurper faces. Both Henry IV and Henry V (particularly on the eve of the battle of Agincourt) are unhappily aware of the fact that the crown was acquired in a somewhat nefarious fashion.
O God of battles! steel my soldiers' hearts;
Possess them not with fear; take from them now
The sense of reckoning, if the opposed numbers
Pluck their hearts from them. Not to-day, O Lord,
O, not to-day, think not upon the fault
My father made in compassing the crown!
Let us now move to another country and another century. Tory Historian has been enjoying Earl Stanhope's Conversations with Wellington. Some of the notes refer to little more than day to day chats and gossip. Without knowing the people concerned directly they are of little interest and some of the comments are so mundane that they should have been ignored, except for the fact that Stanhope clearly thought that every word the Duke had uttered and he could recall would be of interest to succeeding generations.
However, among all that trivia, which is, one must admit, often amusing, there are some highly interesting comments and stories from the Duke, about the Peninsular campaign, about Waterloo, about the country as he saw it and about Napoleon of whom he often spoke with great praise.
In October 16 1837 Lord Mahon (as Stanhope then was) met the Duke hunting and immediately plunged into a long conversation, the chief part of which was, apparently, political and was not, therefore, noted down (more's the pity).
Eventually, the conversation turned to Napoleon's Russian campaign and a discussion whether there could have been other decisions the Emperor could have taken and remained victorious in Russia.
The plan I have seen suggested in Ségur's history of the campaign, and ascribed I think to Count ------, was to winter in Moscow and intrench himself, allowing his communications with France to be cut off?And all because that head lay uneasy. The soldiers and officers may have been devoted to him but he could never be certain of the rest of the country.
'He couldn't have done that. You know that when he heard of Mallet's conspiracy at Paris, he said, 'This would not matter to me if I were a Bourbon, but as it is I must endeavour to return directly. In fact, if you look through his campaigns you will find that his plan was always to try to give a great battle, gain a great victory, patch up a peace, such a peace as might leave an opening for a future war, and then hurry back to Paris. This I should say was the great benefit of what we did in Spain - of what we did and enabled the Spaniards to do. We starved him out. We showed him that we wouldn't let him fight a battle at first, except under disadvantages. If you do fight, we shall destroy you; if you do not fight, we shal intime destroy you still.'