Guy Kawasaki said, paraphrasing the point in the video linked above or in [1, 2, 3, 4, 5] (it was also in the biography, "Steve Jobs", by Walter Isaacson): “Steve Jobs has a saying that A players hire A players; B players hire C players; and C players hire D players. It doesn't take long to get to Z players. This trickle-down effect causes bozo explosions in companies.”
"In the United Kingdom, the Foreign Enlistment Act 1819 and the Foreign Enlistment Act 1870 make it unlawful for British subjects to join the armed forces of any state warring with another state at peace with Britain."