It was Johnson’s trip with Lincoln for the historic Gettysburg Address in November 1863 that may have led to his death. Mrs. Lincoln had not wanted her husband to go to Gettysburg because he was ill, but Lincoln insisted and Johnson accompanied him. Lincoln was showing early stages of small pox and Johnson nursed him. Only Johnson later came down with the disease himself and died in January 1864.

“He did not catch it from me,” Lincoln believed. “At least I think not.” Still he felt responsible for Johnson. “William is gone,” he reportedly told a Washington banker. “I bought a coffin for the poor fellow and have had to help his family.”

Rumors also persist that Lincoln buried Johnson in Arlington Cemetery with a tombstone that reads “William H. Johnson, Citizen.” Historians are not so quick to substantiate that, however, since William H. Johnson was a common name on both sides of the color line.

What is known for certain, however, is that Lincoln stood up for Johnson. Prior to Johnson’s death in 1864, a reporter observed Lincoln counting out greenbacks and asked him about it. According to Disunion, the reporter explained that “The president had collected the outstanding wages himself and was dividing them into envelopes in accordance with the porter’s [Johnson’s] wishes.”

Taking it a step further, Lincoln had endorsed a $150 loan Johnson had taken from the First National Bank of Washington. The debt was unpaid when Johnson died and Lincoln insisted upon honoring it even though the bank’s cashier, William J. Huntington, was willing to forgive the debt. Eventually they compromised and Lincoln paid half of the debt, with the other half being forgiven.

But most poignant, Huntington reportedly joked with Lincoln, stating that “After this, Mr. President, you can never deny that you endorse the Negro.” To which Lincoln responded, “That’s a fact!” He also added, “but I don’t intend to deny it.”

For decades, history books have indicated that Lincoln’s relationship with Frederick Douglass was largely responsible for his progressive outlook on race relations when the truth of the matter may be that his relationship, friendship even, with Johnson may have been an even greater influence. Actor Anthony Mackie, who plays Johnson in Abraham Lincoln: Vampire Hunter, believes so.

“It’s exciting when you think about what he meant in the annals of history,” Mackie stated in a recent interview. “He was the friend of the guy who wrote the Emancipation Proclamation, who lead us into the Civil War, and gave the Gettysburg Address. So, it’s partly because of him we are where we are.”

He also told the Daily Beast, “If one kid Googles William H. Johnson and discovers that the Emancipation Proclamation came out of him being Abe Lincoln’s friend, then I’ve done my job.”

And that may indeed be worth entertaining the suggestion that Abraham Lincoln was indeed a vampire hunter during what is arguably this nation’s most defining moment.

Follow Ronda Racha Penrice on Twitter at @rondaracha