DANEGELD \DANE.geld\ n. a tax collected in Anglo-Saxon times to pay off Viking raiders; also DANEGELT

Since a GELD is a tax that was paid to the crown in Anglo-Saxon times, today’s word means literally ‘Dane tax’. The ‘Dane’ bit reflects the fact that although the Viking warriors were not themselves necessarily Danish, they were usually being paid to invade England on behalf of Danish kings.
The first instance of danegeld being paid to prevent Viking raids was in 991 after England, under the reign of King Ethelred the Second, lost the Battle of Maldon. Interestingly, given our monthly theme, the raiders were probably after spoils from the Royal Mint at Maldon.
Here Ipswich was raided. Very soon after that, ealdorman Byrhtnoth was killed at Maldon. And on that year it was decided to pay tax to Danes for the great terror which they made by the sea coast; that first [payment] was 10,000 pounds. Archbishop Sigerīc decided first on the matter. — Anglo-Saxon Chronicle
Note that EALDORMAN, an old spelling of alderman, is allowed in Scrabble!
Collins/CSW/SOWPODS players note that although danegeld has no anagrams, DETANGLE is a valid anagram of its variant spelling danegelt.
1911 C. R. L. Fletcher & R. Kipling School Hist. Eng. ii. 39 It is always a temptation to an armed and agile nation, To call upon a neighbour and to say:—‘We invaded you last night—we are quite prepared to fight, Unless you pay us cash to go away’. And that is called asking for Dane-geld.