January 16th

On this day - 16th January 1939 - Irish Republican Army started their Sabotage campaign in England 

The "S-campaign" against civil, military and economic infrastructure in England lasted from 1939 to 1940 and consisted of bombings and sabotages. 7 people were killed in the attacks and another 96 people were injured. The sabotages had been planed since 1938 by the Irish Republican Army's Chief of Staff, Seamus O'Donovan. The first attack was on January 16th in 1939 when bombs went of in five different places in England. One bomb went of close to a power station in London, another one damaged an overhead cable. The other three bombs went of in Alnwick, north in England, but none of the first bombs caused any causalities.
In 1939 UK declared war on Germany which led to contact between Germany and IRA leaders. Germany was, however, not impressed with IRAs effort. The German intelligence wrote to IRA and requested:

 "The Pfalzgraf Section very urgently requests its Irish friends and IRA members to be so good as to make considerably better efforts to carry out the S-plan, which they received some time last summer, and to be more effectual against military as opposed to civilian objectives."

November 21st

On this day – 21^st of November 1974 – The Birmingham Pub Bombings

The Birmingham Pub Bombings was several explosions in pubs in Birmingham, United Kingdom. A total of 21 people were killed in the explosions, while another 182 were injured. The Provisional Irish Republican Army were most likely the terrorist behind the attack, although they never officially claimed responsibility. They had previously conducted act of terrorism on English land with the goal of getting the British government to withdraw from Northern Ireland. The bombing in Birmingham led to considerable anti-Irish sentiment in UK, and several Irish people living in the area experienced violent attacks against themselves. Six Irishmen were sentenced to life in prison after the attack, but their case were overthrown in 1991 due to unsatisfactory convictions. This attack is the deadliest terror attack in UK between WW2 and the London Bombing in 2005. It is also seen as one of the worst cases of injustice in UK history.

This terrorist attack is not the only deadly result of the conflict between England and Ireland on the 21^st of November. In 1920 were 31 people killed in Dublin as a part of the Irish war for independence.  

One of the pubs after the bombings