Did Protestants get "Thine is the Kingdom etc..." from the Didache? So, I was writing an answer to a question a few minutes ago, and I was going to smugly tell all you Protestants that your "thine is the Kingdom" doxology is so non-Biblical, it's apocryphal.  

Well, it is apocryphal, but if anything it's anachronistically apocryphal as no Protestant between the time of the Reformation,  whenever that was, and the time of Martin Van Buren's presidency, whenever that was, would have had access to said tidbit of apocryphal lore.

The problem is, it's SOOO nearly verbatim. 


  ...for Yours is the power and the glory for ever. Didache Chapter 8


as opposed to


  for thine is the kingdom the power and the glory, now and forever.  


Catholic's have a similar doxology said during Mass, in English it's: 


  ...the kingdom the power and the glory are Yours now and forever


and I always console myself when praying with Protestants that I'm not doing anything unTraditional in saying their doxology (any more than I am in saying trespasses instead of debts).

But, how did it come about, and what, if anything does the English version of the Protestant ending to the Lord's Prayer have to do with the Didache?
In the record of the Lord's Prayer in Matthew 6, the additional phrase appears in the 1611 edition of the KJV, the Tyndale Bible, and, it appears, in the German Luther Bible of 1545. 

I can't read German, except for "Amen", but it looks like it's there.


  And lead us not into temptation, but deliver us from evil: For thine
  is the kingdom, and the power, and the glory, for ever. Amen.  Matthew
  6:13 KJV
  
  And leade vs not into teptacion: but delyver vs fro evell. For thyne
  is ye kyngedome and ye power and ye glorye for ever. Amen.  Matthew
  6:13 Tyndale, 1525
  
  Und führe uns nicht in Versuchung, sondern erlöse uns von dem Übel.
  Denn dein ist das Reich und die Kraft und die Herrlichkeit in
  Ewigkeit. Amen.  Matthew 6:13 German Luther Bible, 1545


These translations are at the very beginning of the Protestant Reformation, and Tyndale's even predates it a bit.  

This phrase does represent a variant in the Greek Manuscripts, but the origin is in the Greek.

So, this doesn't come from the Didache, but from Matthew's Gospel.