Fortunately for Force W, the Germans were having trouble moving a balanced force forward and keeping them supplied. The Germans attacked the junction between the 1st Rangers and the 2/8 Australian Battalion on 12 April. The Rangers and 2/8th were only able to withdraw with difficulty. Fortunately, the plans for the rearguard position worked and the Germans were delayed there. The 1st Armoured Brigade Group subsequently withdrew to Grevena.
Meanwhile, the New Zealand Division had been active. Their divisional cavalry had armoured cars and Brend carriers before the Olympus Pass. The 16th Australian Brigade was sent across country, to keep the roads free. This only was done with difficulty. By 14 April, the 17th Australian Brigade was arriving from the Piraeus to reinforce the ANZAC Corps, commanded by General Blamey. The situation was deteriorating as the Greek divisions were in obvious trouble and in danger of collapse. The ANZAC Corps was planning withdrawal, starting on 15 April.
This is based on the account in Vol.II of the Official History.