(Those haircuts they're getting there are unique and interesting too -- except in the monastery!)
They were the anti-Beatles. US GIs drafted in the Army in the 60s, serving in Germany. When the Cuban missile crisis happened, they were told to watch the Berlin Wall for attackers.
They shared concert bills with Jimi Hendrix (they were on the same label) and Bill Haley (Rock Around The Clock).
They met in the rec hall and formed a band (surf/R&B) but had to change to the beat sound when the Beatles came to prominence. So they used a banjo for a crunchy bass sound and cut the opposite of a Beatles haircut (shaved out the middle) and wore rope ties.
They did a few reunion shows about a decade ago (their first US shows ever) but at 2 members have since passed on (including the singer).
https://www.youtube.com/watch?v=0XhpXUt82zA