Explanation:

1 is incorrect. British were not invovled in the french revolution of 1789.

2 and 3 are correct. The British army suffered major reverses in the First Afghan war(1838-42) and in the crimean war (1854-56), which shattered the general belief in the invincibility of the British regime.

4 is incorrect as Boers war (1899-1992) occured after the revolt.