The answer lives in this podcast
What was the IRA's S-Plan bombing campaign in Britain in 1939?
In January 1939, the Irish Republican Army launched the S-Plan — a coordinated sabotage campaign targeting Britain. Bombs were planted at railway stations, banks, post offices, and London Underground infrastructure across London, Birmingham, Bristol, Liverpool, and Blackpool. The campaign reached its deadliest point in August 1939, when a bicycle bomb detonated in Coventry city centre, killing five people aged between 50 and 82.
A campaign built on infrastructure sabotage — not random violence
The S-Plan was a deliberate strategic operation, not an improvised campaign. The IRA selected its targets methodically: transport hubs, financial institutions, and communications infrastructure were all in scope. The aim was to inflict economic disruption and political pressure on the British government at a moment when Europe was on the brink of another world war.
Tom Holland examines this period in detail in The Rest Is History, situating the S-Plan within the longer arc of Irish republican violence and the tensions that would eventually erupt into the Troubles decades later. The campaign underlines how the conflict between the IRA and Britain was never purely local to Northern Ireland — it had always carried an international dimension.
Coventry, August 1939 — the bombing that defined the campaign's legacy
The Coventry attack stands apart from the rest of the S-Plan in sheer human cost. A bomb concealed in a bicycle exploded in the city centre, killing five civilians. The ages of the victims — the youngest 50, the oldest 82 — made the atrocity impossible to frame as collateral damage from a military operation. They were ordinary people, not state actors.
This single incident generated enormous public hostility toward the IRA in Britain and demonstrated the fundamental problem with targeting civilian infrastructure: the unpredictability of who dies. As covered in this episode of The Rest Is History, the Coventry bombing foreshadowed the moral and political contradictions that would haunt the IRA for the next half-century.
"At the peak of the violence in the early 1970s, almost 500 people were being killed every year and a bomb was going off in Belfast every single day."
— From The Rest Is History, Episode 697: The Troubles: Murder in Belfast (Part 1). This figure contextualises the scale of what the S-Plan's tactics eventually grew into over the following decades, as the IRA's campaign evolved far beyond the 1939 mainland bombings.
The figures from the 1970s — explored further in The Rest Is History — make clear that the S-Plan was only the opening chapter of a much longer and far bloodier story. The logic of targeting civilian life, first tested in 1939, would return with devastating effect during the Troubles.
What the S-Plan also reveals is that by 1939, the IRA had already concluded that constitutional politics alone would not deliver a united Ireland. The decision to bomb Britain was a direct expression of that frustration — a pattern that, as Tom Holland traces across the series, would repeat itself in different forms for decades to come. Listeners following the full arc of the conflict can explore that trajectory through The Rest Is History podcast.
See also
What violence accompanied the early years of Northern Ireland between 1920 and 1922?
Between the summer of 1920 and the summer of 1922, intense street fighting between the IRA and security forces — especially in Belfast — resulted in more than 500 people killed, 10,000 Catholics driven from their jobs, and 25,000 Catholics expelled from their homes in Northern Ireland.
What was the demographic makeup of Northern Ireland at its creation?
Northern Ireland was established with a two-thirds Protestant majority and one-third Catholic minority, meaning approximately half a million Catholics lived within its borders from the very outset — a structural tension that shaped every decade of the state's existence.
What were the origins of the partition of Ireland and when did it happen?
In 1912, almost half a million unionists led by Sir Edward Carson signed a covenant pledging to use all means necessary to fight against home rule from Westminster — setting in motion the chain of events that would lead directly to partition.
Key takeaways
- The S-Plan launched in January 1939 targeted transport, banking, and postal infrastructure across five British cities simultaneously.
- The Coventry bicycle bomb of August 1939 was the campaign's deadliest attack, killing five civilians — all aged 50 or older.
- The S-Plan demonstrated that the IRA's campaign was never limited to Northern Ireland; it carried a mainland British dimension from the beginning.
- The tactics first deployed in 1939 foreshadowed the far more lethal violence of the Troubles era, when nearly 500 people were being killed per year at the peak of the conflict.
This question was answered in Episode 697 of The Rest Is History. Listen to the full episode and explore the entire podcast on Listenly.
Listen to the episode on Listenly