During the Home Rule Crisis of 1912–14, he defied the British government in preparing an armed resistance in Ulster to an all-Ireland parliament.

He accepted partition as a final settlement, securing the opt out of six Ulster counties from the dominion statehood accorded Ireland under the terms of the 1921 Anglo-Irish Treaty.

Craig enlisted in the 3rd (Militia) battalion of the Royal Irish Rifles on 17 January 1900 to serve in the Second Boer War.

He was seconded to the Imperial Yeomanry, a cavalry force created for service during the war, as a lieutenant in the 13th battalion on 24 February 1900,[2][3] and left Liverpool for South Africa on the SS Cymric in March 1900.

On his recovery he became deputy assistant director of the Imperial Military Railways, showing the qualities of organisation that were to mark his involvement in both British and Ulster politics.

In 1905, he had co-founded the Ulster Unionist Council to coalesce loyalist opposition to Irish Home Rule in northern province.

In a massed demonstration in Belfast, Edward Carson, the Dublin barrister he had nominated for the leadership of the UUC, led in signing the Ulster Covenant.

The signatories pledged "to stand by one another in defending for ourselves and our children our position of equal citizenship in the United Kingdom", and to use "all means which may be found necessary to defeat the present conspiracy to set up a Home Rule Parliament in Ireland".

In April 1914, Craig supported Major Frederick Crawford in arming the Ulster Volunteers (UVF) with rifles and ammunition purchased, and smuggled, from Imperial Germany.

[14] In the months that followed WSPU militants were implicated in a series of outrages against property that, in addition to arson attacks on Unionist-owned buildings and on male recreational and sports facilities,[15] included forced entry into Craig's home.

[16] On 3 April 1913 police raided the flat in Belfast Evans was sharing with local activist Midge Muir, and found explosives.

[14] Following the United Kingdom declaration of war upon Germany in August 1914, Craig persuaded Lord Kitchener to remould the UVF into the 36th Ulster Division.

He was given the rank of lieutenant-colonel, but unift for front line service he resigned his commission at the end of 1916 and took up a junior post, Treasurer of the Household, in the wartime coalition government of Lloyd George.

In February 1921, with the war of independence underway in the south, Craig succeeded Edward Carson as leader of the Ulster Unionist Party.

Writing to Prime Minister David Lloyd George, Craig had declared that it was only as a "sacrifice in the interest of peace" that unionists would accept a Northern Ireland parliament they had not asked for.

[20] To make such assurance against British pressure for Irish unity doubly sure, in November 1921 Craig suggested to Lloyd George that Northern Ireland's status be changed to that of a Crown dominion outside of the United Kingdom.

Although in signing the Anglo-Irish Treaty, only weeks later the Prime Minister conceded Southern Ireland precisely this Canada-style form of statehood, to Craig he replied that he was not willing to give "the character of an international boundary" to "a frontier based neither upon natural features nor broad geographical considerations".

[21] Lloyd George was nonetheless persuaded in October 1920 to secure that still unsettled frontier by endorsing Craig's proposal for a new "volunteer constabulary ... raised from the loyal population" and "armed for duty within the six county area only".

[26] In April 1934, in response to George Leeke's question regarding the Protestant nature of the Unionist dominated parliament, Craig famously replied: The hon.

In April 1939, and again in May 1940 in the Second World War, he called for conscription to be introduced in Northern Ireland (which the British government, fearing a backlash from nationalists, refused).

[30] He also called for Churchill to invade Ireland, alternatively known as Éire, using Scottish and Welsh troops in order to seize the valuable ports and install a Governor-General at Dublin.

[33] His wife, Cecil Mary Nowell Dering Tupper (Viscountess Craigavon), whom he married on 22 March 1905 after a very brief courtship, was English, the daughter of Sir Daniel Tupper, assistant comptroller of the Lord Chamberlain's department of the king's household, and a fourth cousin of the future Queen Mother, Elizabeth Angela Marguerite Bowes-Lyon.