The Knickerbocker cocktail first appeared in 1862 in "Bartenders Guide: How to mix drinks" by Jerry Thomas. The Knickerbockers are a little sneaky, the sweetness of the syrup and the refreshing side brought by the lemon indeed manage to make you forget the alcohol content rather well. It is a cocktail almost identical to the White Lion published in the same book.
Jerry Thomas republished in 1887 in the 3rd edition of his "Bar-tenders Guide" the Knickerbocker recipe, this final version invites to strain the contents of the shaker into a cocktail glass without ice.
Jerry Thomas invites us to add raspberry syrup if the cocktail is not sweet enough for our taste and leaves us the choice of the type of lemon. Moreover, his original recipe from 1862 called for the use of Santa Cruz rum.
It is not known who invented the knickerbocker or why this cocktail is called that, but there are at least some hypotheses as to the origin of its name. Before 1862 (first publication of the recipe), the term "Knickerbocker" appeared in different forms: the Knickerbocker Boat Club created in 1811, the Knickerbocker Base Ball Club created in 1845, and also Diedrich Knickerbocker which was a pseudonym exploited by the writer Washington Irving as early as 1809.