This is a ficticious scenario but very likely many events like the one described
took place during the British 8th Armies retreat to El Alamein.
In June 1942 After the failure of operation Gazala and the loss of Tobruk with the 8th
Army  in full retreat towards El Alamein. On the outskirts of Sidi Barrani an
hasty little reagaurd roadblock is thrown together, with orders to delay leading 
elements of the attacking Panzer Divisions. A mission with little hope of survival,
but often very neccessary in warfare. An early morning mist blowing in off the sea has 
reduced visibility  to about 500m