Siege of Tobruk
The Allies wanted to control Tobruk so that they could defend Egypt and the Suez Canal.   When the Axis armies could no longer use the port at Tobruk, they had to bring in supplies at the distant port of Tripoli.  This required the Axis armies to bring the supplies by truck through  of desert.  After the Allies won Tobruk, the Axis armies continuted fighting to take it back.  The Axis armies fired many artillery shells at Tobruk and dropped many bombs on the town.