I've been analysing Winston Churchill's speeches a lot recently and I noticed that he tends to say the "harsh truth" in his speeches in order to gain credibility for his claims/himself. Here's an example from the speech Give Us The Tools:
(Hitler's) clutching fingers reach out on both sides of us into the ocean. I have never underrated this danger, and you know I have never concealed it from you. Therefore, I hope you will believe me when I say that I have complete confidence in the Royal Navy...
What is the technical term for this in terms of rhetorical devices?