1) As a noun, ‘spoil’ referred initially to loot or plunder, that is the ‘spoils of war’ and it was only much later that it came to be associated with damage.
A Ripon document is quoted in the OED as the first use of the word to imply that the landscape had been spoiled or ‘rendered unserviceable’: 1609 Commons, Wastes, Spoils, Heaths, Moors followed almost immediately by the spoil of the same Woods. Similarly, a survey of the king’s woods in the North Riding, in 1608, lists several woods in the East Ward and then has a marginal note saying Waste followed by it is not above 16 or 17 yeares since that they weare spoyled. In fact it is not certain that we should understand ‘spoil’ in these cases to mean ‘damage’, since ‘the spoils’ were assets, like the ‘wastes’.The meaning may be that the trees had been illegally lopped and topped – plundered that is. If that is the correct interpretation, it marked a transitional stage in the word’s meaning: in a survey of 1568 it was said that theire hath bene muche spoile and wayst maid in the said Park of Blansbye … to the value of one thousand lodes and at the Leeds manor court in 1666 Richard Maud presented a tenant for trespass of swine eating and spoyling his grass. Be that as it may, ‘spoil’ in the sense of refuse material from industrial workings, and the verb to spoil, are first noted in the seventeenth century, explicitly linked to damage done by coal-mining. Leaseholders of the Earl of Cumberland’s pits in Craven were required in 1629 to deliver up the work site unspoiled and tennentable at the end of their term. Compensation was made further south in 1699 for the spoile and damage done to the … owners of the respective lands and grounds, Goldthorpe. The modern meaning was by then established: 1702 no unnecessary spoyle or destruccon, Thornton
1732-3 if the Spoil and damage done to my lands … was to be added to the Expences it would reduce the neat profits, Horsforth.