Final answer:
The Beatles' "Revolution 1" is considered their first explicitly protest song that comments on the political and social issues of the time, differentiating from their prior themes of love and experimental music styles.
Step-by-step explanation:
The song "Revolution 1" by The Beatles from their 1968 self-titled album, commonly known as the 'White Album,' is the group's first explicitly protest song. Written by John Lennon, the song addresses the political and social unrest of the time, expressing skepticism towards those calling for violent revolution.
Although The Beatles had previously touched on themes of love and romance, and had experimented with various music styles and production techniques, "Revolution 1" marked their music's shift towards a clear protest narrative. With its laid-back groove and bluesy feel, it also stands out as an experiment in how a protest song can be delivered in a more reflective tone.