People living in fear of constant attacks are in a state of high anxiety and exhaustion, especially as they have a lot of hard physical work to do. This makes some of their judgements a little odd, but this is a spectacular example of what can go wrong. Some more from Highways and Byways of Dorset by Joseph Penny:
“The very last call to arms to which the poor, war-worn, battered town of Wareham responded was the most remarkable summons of all. Possibly no garrison ever sprang to its feet and manned it trampled ramparts in obedience to a cry more astonishing. It ws to repel a phantom army, which was creeping upon the town like a deadly mist, that the men of Wareham rose and rushed into the streets, buckling on their swords and priming their pistols. The warning came at the close of a winter’s day in this wise. Between Wareham and the sea is a height called Grange Hill, It is on the way to the old Celtic camp of Flowers Barrow, which crowns the white cliffs of WarbarrowBay. One evening in December, 1678, Captain John Lawrence of Creech, his brother, four clay-cutters, with other simple folk, were struck with horror at the sight of several thousands of armed men marching over Grange Hill from Flowers Burrow. The brothers Lawrence and the claycutters ran for their lives to Wareham to alarm that often alarmed town. Wareham was prompt. Before the ghostly army could draw in sight three hundred of the miltia were called out, the bridge “Barricadoed,” and all the boats were drawn over to the north side of the river. Captain Lawrence and his brother, being convinced that the safety of England was imperilled, rushed post haste to London and “Deposed the particulars on oath before the Council.” The loyal country of Dorset, in them meanwhile, called together some thousands of armed volunteers.
Yet nothing came of it all. There was no invading army … In the hurry of the preparations for defence no one seemed to have thought it well to walk over to Grange Hill and take a look at the direful force. The army that was moving that winter’s night upon unhappy Wareham was a fabric of the brain. It is conjectured by some that the delusion was brought about by clouds gliding over the downs, or that the light of the setting sun threw terrifying shadows from the boulders and the gorse bushes on the hill. No doubt the harried folk around Wareham had invading armies “on the brain”, ad from frequent alarms become frightened at their own shadows, and so were ready to fly to the ramparts to defend themselves from an on-rolling mist. Captain Lawrence and the clay-cutting visionaries escaped punishment for this inconvenient dreaming of dreams. The story deposed on oath before the Council would have been more readily excused had not he imaginative Lawrence declared that this grey ghost of formless men approached “with great clashing of arms”. Such was the last call to arms that rang through the streets of Wareham, a trumpet blast that summoned the garrison to fight an army of shadows.