- Pr uss ian ▁War ▁because ▁of ▁fear s ▁that ▁they ▁were ▁a ▁threat ▁to ▁the ▁Republic . ▁ ▁During ▁the ▁ 1 9 th ▁century , ▁the ▁Bre ton ▁language ▁started ▁to ▁decl ine ▁precip it ously , ▁mainly ▁because ▁of ▁the ▁Fran ci z ation ▁policy ▁conducted ▁under ▁the ▁Third ▁Republic . ▁On ▁one ▁hand , ▁children ▁were ▁not ▁allowed ▁to ▁speak ▁Bre ton ▁at ▁school , ▁and ▁were ▁pun ished ▁by ▁teachers ▁if ▁they ▁did . ▁Fam ously , ▁signs ▁in ▁schools ▁read : ▁" It ▁is ▁forb idden ▁to ▁speak ▁Bre ton ▁and ▁to ▁sp it ▁on ▁the ▁floor " ▁(" Il ▁est ▁inter dit ▁de ▁par ler ▁Bre ton ▁et ▁de ▁cra cher ▁par ▁terre "). ▁▁ ▁At ▁the ▁same ▁time , ▁the ▁C elt ic ▁Rev ival ▁led ▁to ▁the ▁foundation ▁of ▁the ▁Bre ton ▁Regional ist ▁Union ▁( UR B ) ▁and ▁later ▁to ▁independence ▁movements ▁linked ▁to ▁Irish , ▁Wel sh , ▁and ▁Scottish ▁independence ▁parties ▁in ▁the ▁UK , ▁and ▁to ▁pan - C elt ic ism . ▁However , ▁the ▁audience ▁of ▁these ▁movements ▁remained ▁very ▁low ▁and ▁their ▁ideas ▁did ▁not ▁reach ▁a ▁large ▁public ▁until ▁the ▁ 2 0 th ▁century . ▁The ▁Se iz ▁Bre ur ▁movement , ▁created ▁in ▁ 1 9 2 3 , ▁permitted ▁a ▁Bre ton ▁art istic ▁rev ival ▁but ▁its ▁t ies ▁with ▁Naz ism ▁and ▁the ▁collaboration ism ▁of ▁the ▁Bre ton ▁National ▁Party ▁during ▁World ▁War ▁II ▁weak ened ▁Bre ton ▁national