was assimilated
And Filip became Pilip. No longer used today as a Christian name but still encountered in certain surnames such as Pilipiak, Pilipski, Pilipowicz, etc.
Voltaire
An anecdote that comes to mind is an exchange between Voltaire and Friedrich der Große. In the convention of the riddles and word-games popular at the time, the Prussian emperor sent Voltaire an invite which read:
P/venez à ci/sans.
Voltaire répondit: G a.
Can anybody make any sense of it?
Hint: If handwrittten, the slash (diagonal) should actually take the form of a horizontal fraction bar, unavailable (as far as I know) on my comptuer to separate the top element from the bottom one.