...and again, and again, and again...

an organized massacre of helpless people

I thought its a typo for program or something, turns out it's a real word:

A pogrom is a violent riot incited with the aim of massacring or expelling an ethnic or religious group

@shasta technically speaking it's organized violent persecution of an ethnic group. Historically has a more specific meaning as it originates in Russia.

When the Russian Empire expanded and in the 19th century began to colonize /occupy territory that contained significant ethnic Jewish populations, they undertook a lot of rioting to lynch/massacre/expell them. These were known as "pogroms".

In modern English it means this kind of systematic attack against any ethnic group. It is also sometimes used informally/metaphorically for other things e.g. political or corporate "pogroms" against a particular group or class of people.

Essentially, (if my high school history had it correct) it's an extreme form of violence designed to force a targeted people to leave the land they are living on. People used to use this term a lot more in older days (back in the 80s), but now we just use the term genocide since pogroms usually are an aspect of genocide - the Armenian Genocide, for instance, had a lot of pogroms going on. They are also a key aspect of settler-colonialism - which is how Palestinians ended up being one of the largest refugee populations in the world.