The situation of Protestantism in 1530 was critical. The Diet of Speier had forbidden the further progress of the Reformation: the Edict of Worms was in full legal force; the Emperor had made peace with the Pope, and received from him the imperial crown at Bologna; the Protestants were divided among themselves, and the Conference at Marburg had failed to unite them against the common foe. At the same time the whole empire was menaced by a foreign power. The Turks under Suleiman “the Magnificent,” who called himself “Lord of all rulers, Dispenser of crowns to the monarchs of the earth, the Shadow of God over the world,” had reached the summit of their military power, and approached the gates of Vienna in September, 1529. They swore by the beard of Mohammed not to rest till the prayers of the prophet of Mecca should be heard from the tower of St. Stephen. They were indeed forced to retire with a loss of eighty thousand men, but threatened a second attempt, and in the mean time laid waste a great part of Hungary.
Under these circumstances the Diet of Augsburg convened, April 8, 1530. Its object was to settle the religious question, and to prepare for war against the Turks. The invitation dated Jan. 21, 1530, from Bologna, carefully avoids all irritating allusions, sets forth in strong language the danger of foreign invasion, and expresses the hope that all would co-operate for the restoration of the unity of the holy empire of the German nation in the one true Christian religion and church.
So Schaff. It was the Diet of Augsburg which provoked the production of the Augsburg Confession. And Melanchthon’s ‘Apology of the Augsburg Confession’. And remember, apology means ‘defense’, not something else.