There is always a moment in every war when wary inaction gives way to movement, bred of an access of boldness to one side or the other.
Gustavus had received an addition of eight thousand Swedes and six thousand English. He had persuaded George William, the Brandenburger, to throw in his lot with him. Pappenheim and Tilly had made, but not followed up, an abortive attack on his fortified camp at Werben. He decided to cross the Elbe and advance to the southern limits of Mark Brandenburg, whether the Emperor's generals resisted him or not. It is possible that he thought such an advance would assist John George of Saxony, whose territory lay next in his path, to make up his mind.
And at this time the Emperor Ferdinand was aware that Count Fürstenberg, his chief commander in Austrian Italy, had arrived by leisurely marches with twenty thousand veteran troops by way of Franconia and the upper Palatinate, to join Tilly's army, so that, like Gustavus, he also intended to assist John George of Saxony to make up his mind.
To Pappenheim, Tilly being still at Erfurt, or in the confines of Thüringia, Nigel brought word of the advance of Gustavus. Pappenheim sent word to Tilly, and Tilly returned to concert operations.
They had scarcely joined hands again when the Emperor's messenger arrived bidding them forthwith march into Saxony.
Imperial courtesy demanded that the Emperor's general should give John George at least a single opportunity of submission. Two officers of high rank were sent to the Elector with an imperious demand. John George made a dignified reply as became a prince, entertained the officers with Saxon hospitality as a prince, and at the close of the banqueting uttered this dry and humorous warning:—
"Gentlemen, I perceive that the Saxon confectionery, which has been so long kept back, is at length to be set upon the table. But, as it is usual to mix it with nuts and other hard ingredients, I pray you to take care of your teeth."
In a short space Tilly was before Leipzig, threatening it with fire and sword, and the fate of Magdeburg; and Pappenheim was thirty miles to the west taking possession of Merseburg.
Then John George made up his mind.
Then rode messengers offering alliance to Gustavus, who, ever mindful of a possible evil day and a clear line of retreat, demanded the fortresses he had asked for before.