The Greek withdrawal from the salient

 After the latest moves ordered, the "boundary between the Greek and British forces would be a north-south line that ran through Deskati. One consequence was that the 1st Armoured Brigade would need to move east. The Greeks had the problem that they would need to  march one hundred miles. Someone would need to hold two passes, the Klisoura and the Siatista passes. Someone would also need to hold the Grevena road for several days. That would be necessary to be able to execute the "retirement"

At General Wilson's headquarters, they learned that "the road through Grevena" was blocked by slow-moving Greek troops trying to march to the south. The report said that the Greek 12th and 20th had "disintegrated" on their move towards Athens. The Australian historian was saying that the Greeks were not in such a poor condition, and that their appearance made it look worse than it really was. 

Apparently General Wilson considered that there was a "serious threat to his inland flank". General Wilson ordered the 17th Australian Brigade, then unloading at the Piraeus, "to guard the inland flank". Sometime on 13 April, the 17th Brigade commander arrived at General Blamey's headquarters. At this point, General Wilson was located at Blamey's headquarters. 

Brigadiier Savige, the 17th Brigade commander, "drove from Larisa to Kalabaka". They did not see any Greek troops during their travels. After that, they drove to Pindus, "above the snow line where they could see the Adriatic". They drove back to Kalabaka, which by then was "crowded with Greek troops." By the next morning, Savige was called back to Blamey's headquarters. "While they were talking, word arrived that the Germans had broken through on the left". Blamey then ordered the 17th Brigade to hold a line "covering Kalabaka". This is based on the account in "Greece Crete and Syria" by Gavin Long.