May 1919 The Partition of Ireland
The Afghan government seized the opportunity to invade India, starting a border war that lasted most of the summer. All this at a time when Sinn Féin had declared independence and Ireland was sliding into the vortex of terror and counterterror, tying down some 30,000 British troops by the winter of 1919-20.
Field Marshal Sir Henry Wilson, a die-hard Irish Unionist who was later gunned down by the IRA, warned that:
“Surrender to the murder gang in Ireland,” an integral part of the UK, would have “a deplorable and very immediate effect” on nationalist agitators in Egypt and India.
Source: Reynolds, David. The Long Shadow (p94). Jeffery, ed., Military Correspondence, pp. 288-9; see generally John Gallagher, “Nationalisms and the Crisis of Empire, 1919-1922,” MAS 15 (1981), pp.355-68.