The good government of Athelstan and his successors kept the country free from foreign freebooters, but when Ethelred II., called the Unready (or rather the Redeless), came to the throne, the Danes saw their opportunity. In 991 he tried to bribe his enemies to stay away, and was the first English King to institute the Danegelt, which was for so many years a severe tax upon the resources of the country. The bribe was useless, and the enemy had to be bought off again. A Danish fleet threatened London in 992, and in 994 Olaf (or Anlaf) Trygwason (who appears first as harrier of English soil in 988), with Sweyn, the Danish King, laid siege to London, but failed to take it. They then harried, burned and slew all along the sea coasts of Essex, Kent, Sussex and Hampshire. The English paid £10,000 to the Danes in 991, and in 994 they had to produce the still larger sum of £16,000 in order to purchase peace. Olaf then promised never again to visit England, except in peace. Subsequently Ethelred brought disaster upon himself and his country by his treachery. In 1002 he issued secret orders for a massacre of all the Danes found in England, and in this massacre Gunhild, sister of Sweyn, was among the victims. In consequence of Ethelred's conduct the Danes returned in force to these shores and had to be bought off with a sum of £36,000. They came again and made many unsuccessful assaults upon London, upon which the Chronicler remarks: 'They often fought against the town of London, but to God be praise that it yet stands sound, and they have ever fared ill.'