With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: In the summer of 1941, Wheeler and three of his batteries were assigned to fight against German and Italian forces in the North African Campaign. In September, they set sail from Glasgow aboard the RMS "Empress of Russia"; because the Mediterranean was controlled largely by enemy naval forces, they were forced to travel via the Cape of Good Hope, before taking shore leave in Durban. There, Wheeler visited the local kraals to compare them with the settlements of Iron Age Britain. The ship docked in Aden, where Wheeler and his men again took shore leave. They soon reached the British-controlled Suez, where they disembarked and were stationed on the shores of the Great Bitter Lake. There, Wheeler took a brief leave of absence to travel to Jerusalem, though his absence from Petrie on his hospital deathbed was noted. Back in Egypt, he gained permission to fly as a front gunner in a Wellington bomber on a bombing raid against Axis forces, to better understand what it was like for aircrew to be fired on by an anti-aircraft battery.
text_B: Was the situation at the Great Bitter Lake critical to the point that no one could leave their post?
NO.