"No pasaran!"
by cm

French Propaganda Poster, 1918
Public DomainFrench Propaganda Poster, 1918 - Credit: Maurice Neumont
"They shall not pass!" in Spanish.

A rallying cry for defenders, famously uttered by Isidora Dolores Ibárruri Gómez, a communist Republican leader, during the Siege of Madrid (1936-1939).  When Franco took Madrid, he retorted - three years on - with the words Hemos pasado ("We have passed").

The origin of the phrase may have been the Battle of Verdun, when General Robert Nivelle rallied his troops with the line "Ils ne passeront pas!".  The phrase was later inscribed on the badges of units serving on the Maginot Line.