Lincoln, told that Grant drank, asked for the brand so that he could recommend it to his less successful generals. Most of his cabinet drank—sometimes in the mornings or at lunch. Although Lincoln was a teetotaler—he didn't like the taste—he thought that, by and large, drinkers were as capable as teetotalers.
Drinking on the job, in some occupations, was once as common as the coffee break. Now, it is a good way to get your-self fired. Churchill drank around the clock (or it seemed that way), Truman had a nip before breakfast. Eisenhower, while president of Columbia, sometimes had three martinis with his lunch.
Times have changed. A lawyer might be forgiven for showing up after lunch with gin on his breath, but doctors wouldn't dare. Bankers, yes; clergymen, no (except for some denominations?).