Fail

I don't believe he actually read it, even though if he did, I can easily believe he didn't get the message.

Aides said that the president was furious that Mr. Mattis’s resignation letter — in which he rebuked the president’s rejection of international allies and his failure to check authoritarian governments — had led to days of negative news coverage.

When Mr. Trump first announced that Mr. Mattis was leaving, effective Feb. 28, he praised the defense secretary on Twitter. One aide said that though Mr. Trump already had the resignation letter when he praised Mr. Mattis, he did not understand just how forceful a rejection of his strategy Mr. Mattis had issued.

[...]

[Patrick M.] Shanahan [the acting Secretary of Defense], who, like Mr. Mattis, is from Washington State, is a former Boeing executive. Aides say that Mr. Trump likes him in part because he often tells the president that he is correct to complain about the expense of defense systems.

  MSN

He doesn't hear that last part. All he needs to hear is that he's correct.

...but hey, do what you want...you will anyway.