There were two main periods of clearance -- 1785-1820 and 1820-50. The first came about with the introduction of sheep in Easter Ross, Knoydart, Glen Garry, the Uists, Skye, Tiree, and above all the vast estates of Elizabeth Countess of Sutherland. Townships were cleared and sometimes burnt, tenants and their livestock evicted, and the land enclosed to create sheep runs. Although emigration offered a last-resort escape from these atrocities, it was discouraged by landowners, mostly clan chiefs who felt the need for retainers and labour for kelping and the government who needed Highland troops for the Napoleonic wars.
Around 1820 the demand for cattle and kelp declined dramatically. The tenants were unable to meet their rents; the landlords, faced with a fall in receipts, either resigned themselves to further clearances or sold out to those who would. Emigration now became a serious alternative. The climax came with the potato famine of 1846 when many now saw emigration as the only solution and clearances were therefore justified on humanitarian rather than purely economic grounds. However, the ravages of the 1840s had relieved population pressures while an upsurge in the market for fish and agriculture products assisted crofting incomes and so landowners' rents.
Whether the evil of the clearances can be attributed to the greed of landlords depends on one's social perspective and the evidence selected. Estate records often contradict the popular mythology; population figures contradict the notion that clearance boosted emigration. On the other hand there is no question that clansmen felt betrayed by those whom they had once regarded as chiefs and protectors and, in many cases, disgusted by their expensive absentee habits, sentiments which only strengthened when estates passed to non-Highland and non-Gaelic proprietors.
Given the widening gulf of class, language, and often religion between landlord and tenant, it is hardly surprising that feelings ran high. But the famine and the relief measures undertaken to ameliorate it also brought the plight of the crofters to the attention of a wider audience. The Napier Commission and the Crofters' Holdings Act put an end to the clearances and reversed the plight of the crofters.
Adapted from The Collins Encyclopedia of Scotland, 1994.