Billy Wilder was a true Renaissance man in the film business, the first person to win Academy Awards as a producer, director, and screenwriter—for the same film. That's a massive accomplishment.
Before he'd achieve that feat with 1960's The Apartment, however, Wilder directed and co-wrote The Lost Weekend. This thing was no slouch either: it won Academy Awards for Best Picture, Best Adapted Screenplay, and Best Director, not to mention Ray Milland's win for Best Actor. It also represents the capstone to what was likely Wilder's hottest streak as a director.
Wilder had just finished writing and directing 1944's Double Indemnity, which earned him serious cred as a director of moody film noir. Wilder would employ many of the directorial technique he learned on that film in The Lost Weekend, giving it that same dark film noir energy while still creating something wholly unique.