The singer recalls when "Lord Antrim's men came down yon glen" While some opposed them "our 'Prentice Boys" closed the gates. The seige is recounted including Walker's and Murray's parts. "When we close our gates again We'll then all be True Blue"
The Protestant Plantation of Ulster was created after the 1607 "Flight of the Earls" - heads of the Ulster clans - to Rome allowed James I to declare their lands forfeit to the Crown. In the Plantation, the City of Londonderry was fortified and gated walls built around it. When James brought troops from Ireland Londonderry was left unguarded. On December 7, 1688, Lord Antrim's Catholic "Redshanks" camped outside the city. With the city government undecided as to how to handle the situation, thirteen young "Apprentice Boys" seized the gate keys, drew up the drawbridge and locked the four gates. Antrim's troops withdrew. Lord Mountjoy's Protestant regiment was allowed to garrison the city. To escape the war, residents surrounding areas flooded into the city. Reinforcements sent by William to relieve Derry in April turned away. Then James's attempt at negotiating with Derry failed. Colonel Murray led Protestant troops to the gate, which was opened for them, and the Derry government, which had been willing to negotiate with James, was overturned. Reverend George Walker and Colonel Henry Baker were appointed joint Governors. The seige began "in earnest" on May 5, 1689. On July 28 three ships on the Foyle broke the seige bringing food; captain of the Mountjoy was Michael Browning, who was killed in the battle. The beseigers left on August 1, 1689. (source: Cecil Kilpatrick, "The Seige of Derry: A City of Refuge" at the Canada-Ulster Heritage site)
"True Blue": "A substantial number of the earliest Volunteers, the Belfast First Volunteer Company, also called the Green Company, and another the Blue Company, were identified as belonging to the Orange and True Blue Masonic Lodges. Indeed it seems likely that the Volunteer Companies were a Masonic initiative." (source: Dr Clive Gillis, "Days of Deliverance Part 13: The Providential rise of the Orange Order: What it was and what it was not," posted 5/26/2004, Ian Paisley's European Institute of Protestant Studies site) This seems a simple statement of fact. However, keep in mind this statement from the home page of the EIPS site: "The Institute's purpose is to expound the Bible, expose the Papacy, and to promote, defend and maintain Bible Protestantism in Europe and further afield." Later, in the same article, Dr Gillis explains his antipathy to the Masons and the United Irishmen: "The evaporation of the Protestant Catholic divide from 1780 onwards, which so threatened Protestantism, can only be explained in terms of secret co-operation within Freemasonry."
The Belfast Volunteers were formed in 1778 because of the threat of war between France and Britain. Similar groups formed, became politicized, and supported "those in favour of legislative independence from the British parliament and the removal of impediments to Irish commerce." Henry Grattan and Harry Flood supported this program in the Irish House of Commons. (Source: Moylan) - BS
For a good deal more on the Siege of Derry, see "The Shutting of the Gates of Derry." For Grattan and Flood, see "Ireland's Glory." - RBW