Final answer:
The crisis under King Æthelred the Unready was a period of political and military conflict in England during the late 10th and early 11th centuries, primarily due to Viking invasions.
Step-by-step explanation:
The crisis under King Æthelred the Unready was a period of political and military conflict in England during the late 10th and early 11th centuries.
One major crisis during this time was the Viking invasions, which greatly impacted the stability and security of the kingdom.
These invasions led to widespread devastation and forced King Æthelred to pay large sums of money, known as the Danegeld, to the Vikings in an attempt to buy peace.