Eat soup or drink soup

I learnt it was wrong to say drink soup, but eat soup.

But I found in a book the American author used 'drink soup', are they both correct? Thanks!

At four o’clock on the fourth day—it was the afternoon of February 9, 1744—the cavalcade reached a rest house forty-five miles from Moscow. There they found a message from the empress requesting that they delay their entrance into Moscow until after dark. While waiting, they drank fish soup and coffee and dressed for their presentation to the monarch; Sophia put on a rose-colored silk gown trimmed with silver. Meanwhile,