Ariel served in the Paratroopers Brigade of the IDF and participated as part of that brigade in the Battle for Jerusalem at the beginning of the Six-Day War. This inspired him to write the song "Yerushalayim Shel Barzel" ("Jerusalem of Iron"). The song was based on Naomi Shemer's hit song "Jerusalem of Gold", and borrowed its melody (in turn borrowed from the Basque folk song "Pello Joxepe"). It was his reaction to what he saw as the hyper-patriotism of the Israeli public and media of that time. The "Yerushalayim Shel Barzel" mini-album cover showed Ariel in his military uniform thus giving him the nickname "the singing paratrooper".