"Strived" is an acceptable simple past tense and past participle of the verb 'to strive'. 'Strove' is only a simple past participle. And yes, I am aware that spellcheck will highlight it anyway. This is due to the difference with American grammar.
Every day's a school day. Consider yourself educated.
I'm not quoting Mr Gates and his Micro-soft at you, old boy.
You say "strove" is only a simple past participle. So, let's just be clear here, are you saying that "I strove to defeat Uncle Adolf" is wrong or - worse - American?
PS Perhaps it was the cringe-inducingness of the medal which primed me to be queasy about "they who strived", even if that gets absolved because of some grammar-evolves-can't-we-all-just-get-along-Dr-E? escape clause.