Grant and Lincoln's invitation

[STS Lincolnite]

The account in this article is consistent with what Mrs. Grant wrote in her memoirs.

The first sentence of the article says: "The darkest day of my life," Gen. Grant once told to a friend [emphasis added] "was the day I heard of Lincoln's assassination..."

So who is actually reporting this to the author of the article? Grant or his unidentified friend? Based on the structure of the article, it sounds to me like the author is relaying the words of the "friend". Not that that necessarily negatively impacts the veracity of the account.