Edmund C. Briggs recalls Emma Hale Smith saying JS was ignorant of Jerusalem having walls.
Edmond C. Briggs, "A Visit to Nauvoo in 1856," Journal of History 9, no. 4 (October 1916): 454
While she talked to us the tears flowed from her large, bright eyes like rain, and I could see in every act affection for Joseph.
Delineating her evidence of the divine authenticity of the Book of Mormon, she said: "When my husband was translating the Book of Mormon, I wrote a part of it, as he dictated each sentence, word for word, and when he came to proper names he could not pronounce, or long words, he spelled them out, and while I was writing them, if I made any mistake in spelling, he would stop me and correct my spelling, although it was impossible for him to see how I was writing them down at the time. Even the word Sarah he could not pronounce at first, but had to spell it, and I would pronounce it for him.
"When he stopped for any purpose at any time he would, when he commenced again, begin where he left off without any hesitation, and one time while he was translating he stopped suddenly, pale as a sheet, and said, 'Emma, did Jerusalem have walls around it? When I answered 'Yes' , he replied, 'Oh ! I was afraid I had been deceived.' He had such a limited knowledge of history at that time that he did not even know that Jerusalem was surrounded by walls."