Re: Islamically can you join a national army...
And there you go again... There is no disagreement in terms of racism/nationalism as such.
ALL MANKIND IS ONE COMMUNITY - that is our destination.
I asked you a simple question which I will repeat again:
"Everytime a Khalifa used to passed away ... the ummah were often in the situation of headless state"
This means that either there is something inherently wrong this system that it is exibiting such a symptom, or that this is not what might have occured, and needed to be fabricated to justify monarchy/rule-based-on-lineage (eg, Umayyad, Abbasid, Fatimid).
Look into your own heart, think logically, and then answer.