Thus for a time the Saxons recovered their autonomy, and the great Scandinavian horde retired to East Anglia. Æthelred, Ælfred's son-in-law, was appointed under-king of recovered Mercia. Henceforward, Teutonic Britain remains for awhile divided into Wessex and the Denalagu–that is to say, the district governed by Danish law. Though peace was thus made with Guthrum, new bodies of wickings came pouring southward from Scandinavia. One of these sailed up the Thames to Fulham, but after spending some time there, they went over to the Frankish coast, where their depredations were long and severe. Throughout all Ælfred's reign, with only two intervals of peace, the wickings kept up a constant series of attacks on the coast, and frequently penetrated inland. From time to time, the great horde under Hæsten poured across the country, cutting the corn and driving away the cattle, and retreating into East Anglia, or Northumbria, or the peninsula of the Wirrall, whenever they were seriously worsted. "Thanks be to God," says the Chronicle pathetically "the host had not wholly broken up all the English kin;" but the misery of England must have been intense. Ælfred, however, introduced two military changes of great importance. He set on foot something like a regular army, with a settled commissariat, dividing his forces into two bodies, so that one-half was constantly at home tilling the soil while the other half was in the field; and he built large ships on a new plan, which he manned with Frisians, as well as with English, and which largely aided in keeping the coast fairly free from Danish invasion during the two intervals of peace.