My book Seeking John Campbell contains the following dedication.
It is the result of the discovery that one of the John Campbells I investigated was born in Germany with the surname Philippi. He became a naturalised British citizen in 1902 and returned from Argentina to fight in the British Army in WWI.
His brother, who had remained in Gemany, fought on the opposing side and both survived the war, but not without mental and physical scars.
Twenty years later each of their sons would also fight on opposing sides, both would receive awards for valor, and both would pay the ultimate sacrifice and be killed in action within a few weeks of each other in 1944.