The Manhattan most everyone thinks of when they order a Manhattan is actually not that old of a cocktail. It dates from about the 1930s and is the post-prohibition style Manhattan. Not be confused with the pre-prohibition style Manhattan. From about the 1880s to 1919 the Manhattan remained mostly unchanged till the start of prohibition which brought about the loss of Boker’s bitters and no longer adding a few dashes of orange liqueur.
The two changes that changed the Manhattan from its pre-prohibition to post-prohibition form are changing from Boker’s bitters to Angostura bitters and no longer adding 2 dashes of orange liqueur. The change from Boker’s bitters is because the Boker’s company, which was already struggling financially by the 1910s, completely closed the doors around prohibition and those who knew the secret recipe took it to their graves. I believe in the mid 2000s an old unopened bottle of Boker’s was found and reverse engineered so it is possible to make a similar cocktail to the pre-prohibition one but for the last 90 years this is the only one you could make and thus the flavor most of us are use to. The second change was removing the 2 dashes of orange liqueur. This change had more to do with the transition from pre-prohibition mixing ideologies to prohibition era and post-prohibition mixing ideologies. The hallmark of pre-prohibition mixing ideology was to take a nice base spirit and adding complexity and flavor with small amounts of bitters and liqueurs, with the base spirit still the most forward element. Prohibition era and post-prohibition mixing ideology shifted to making flavorful cocktails where the base spirit blended in with the sodas or liqueurs. Not to say these styles were exclusive to any time period but there was a definite shift in what was popular and sold.
There is no specific genesis of this specific recipe. Realistically it was just 1930s bartenders trying to make Manhattans similar to the ones the pervious generation made, while not having the same ingredients. A product of its time and now the standard method.
Bourbon and Sweet Vermouth are a match made in heaven. The two ingredients flavors profiles pair perfectly. The sweet vermouth adds just enough sweetness to soften the bourbon and the bourbon adds just enough sharp toasted oak volume and flavor to bring down the vermouths strong herbal notes. The addition of just a few dashes of Angostura bitters adds a nice spicy complexity to the cocktail. On their own these are all wonderful ingredients but the proportions elevate this to something out of this world.
Manhattan vs Old Fashioned
Whether its the pre-prohibition or post-prohibition style, the Manhattan and old fashion are for the most part very similar cocktails. The main difference between the two is since the old fashion uses simple syrup/gum syrup to cut the strength of the bourbon, the taste is still a very clean, bourbon forward cocktail. The Manhattan on the other hand comes across with a more mild bourbon taste that is balance against a lightly sweet herbal flavor. So the Manhattan is a slightly sweetened bourbon and herbal flavored cocktail and the old fashion is a slightly sweeter but clean bourbon tasting cocktail.
THE MOST IMPORTANT INGREDIENT
The most important ingredients in the post-prohibition style Manhattan is both the sweet vermouth. The bitters are important but they don’t make or break the cocktail. A little bit more than the bitters though is the sweet vermouth. Sweet Vermouth that is too old will make this cocktail unpalatable and the difference between a normal vermouth and a top self vermouth is like night and day. Vermouth is the defining flavor of this cocktail and for not much more you can buy some amazing sweet vermouths. There isn’t a “bad” sweet vermouth, the cheap stuff is still pretty good, but for 5 bucks more you can buy some top shelf amazing vermouths that will elevate this cocktail to new heights.