Further, Gustavus was a consummate engineer, as fond of the spade as Maurice himself, and a past master of field-fortification. On stepping ashore in Germany he first fell on his knees and prayed, and then picking up a spade began to dig with his own hands. This, it may here be mentioned once for all, was the one point in his system which the Scots could not endure; they always grumbled when called upon to use the spade, and in spite of the King's occasional reproaches, always made less progress with field-works in a given time than any other corps in the army. Lastly, to turn to broader principles, the great innovation of Gustavus, visible in all his reforms, was to match mobility against the old system of weight. He never massed his troops in unwieldy bodies, but distributed them in smaller and more flexible divisions, allowing plenty of space for facility of manœuvre. His order of battle was that which was customary in his time, consisting of two lines with infantry in the centre and cavalry on the flanks; but he always allowed three hundred yards of distance between the first and second line, and erected the practice of keeping a reserve, which had been intermittently observed for centuries, into an established principle. Again, he carefully studied the effective combination of the three arms with a thoroughness unknown since the days of Zizca, supplying artillery to his infantry, and supporting impartially horse with foot and foot with horse. Finally, as the backbone of all, he enforced with a strictness that had never been seen before him the observance of discipline. [Sidenote: 1631.] Such was the Army and such the General to which Mackay's regiment now joined itself. In June 1630 it embarked for Germany as part of the thirteen thousand men which formed the Swedish army, half of the companies at Elfsknaben, the remainder under Munro at Pillau. The latter detachment was wrecked off Rügenwalde, which was held by the Imperialists, and lost everything; but having made shift to obtain arms calmly attacked the Imperial garrison and captured the town--as daring a feat of arms as ever was done by Scotsmen. After several small engagements Monro rejoined his headquarters at Stettin, and in January 1631 Gustavus, who boasted with justice that his army was as effective for a winter's as for a summer's campaign, invaded Brandenburg and marched for the Oder. The Scotch were organised into the famous Scots Brigade, consisting of four picked regiments--Hepburn's, Mackay's, Stargate's, and Lumsden's, the whole under the command of Sir John Hepburn. [Sidenote: May.]