 On 25 April the Germans staged an airborne operation to seize the bridges over the Corinth canal , with the double aim of cutting off the British line of retreat and securing their own way across the isthmus . The attack met with initial success , until a stray British shell destroyed the bridge . The 1st SS Motorised Infantry Regiment ( " LSSAH " ) , assembled at Ioannina , thrust along the western foothills of the Pindus Mountains via Arta to Missolonghi and crossed over to the Peloponnese at Patras in an effort to gain access to the isthmus from the west . Upon their arrival at 17 : 30 on 27 April , the SS forces learned that the paratroops had already been relieved by Army units advancing from Athens . 
