During Michelle Obama's Democratic National Convention speech on Monday, she talked about her family's time in the White House, a house that she said "was built by slaves."

After her speech, people began fact-checking to see if her comment was true. It was. Construction on the White House began in 1792 by black slaves, free black men, laborers and European immigrants.

In a controversial statement, Fox News journalist Bill O'Reilly said the slaves who were tasked with the construction were "well fed and had decent lodgings."

"Slaves that worked there were well-fed and had decent lodgings provided by the government, which stopped hiring slave labor in 1802," O'Reilly said. "However, the feds did not forbid subcontractors from using slave labor. So Michelle Obama is essentially correct in citing slaves as builders of the White House, but there were others working as well."

But Abigail Adams, wife of second president John Adams and the mother of sixth president John Quincy Adams, told a different story.

"The effects of Slavery are visible every where," she wrote in a letter in 1800. "And I have amused myself from day to day in looking at the labour of 12 negroes from my window, who are employd with four small Horse Carts to remove some dirt in front of the house. The four carts are all loaded at the same time, and whilst four carry this rubish about half a mile, the remaining eight rest upon their Shovels.

"Two of our hardy N England men would do as much work in a day as the whole 12, but it is true Republicanism that drive the Slaves half fed, and destitute of cloathing ...  to labour, whilst the owner waches about Idle, tho his one Slave is all the property he can boast."

"It is a given that slavery is an abomination," O'Reilly said on "The O'Reilly Factor." "But reporting the story behind Mrs. Obama's very valid points does not diminish the horror of enslavement, as these dishonest critics allege."

See the full letter here, and read more at The Atlantic.