Palestinians will mark the 76th anniversary of their mass expulsion from what is now Israel, an event that is at the core of their national struggle. But in many ways, that experience pales in comparison to the calamity now unfolding in Gaza.

Palestinians refer to the anniversary, which they will observe on Wednesday, as the “Nakba”, Arabic for “catastrophe”. Some 700,000 Palestinians, a majority of the pre-war population, fled or were driven from their homes before and during the 1948 Arab-Israeli war that followed Israel’s establishment.

After the war, Israel refused to allow them to return because it would have resulted in a Palestinian majority within its borders. Instead, they became a seemingly permanent refugee community that now numbers some six million, with most living in slum-like urban refugee camps in Lebanon, Syria, Jordan and the Israeli-occupied West Bank.

In the Gaza Strip, the refugees and their descendants make up about three-quarters of the population.

Israel’s rejection of what Palestinians say is their right to return has been a core grievance in the conflict and was one of the thorniest issues in peace talks that last collapsed 15 years ago.

Now, many Palestinians fear a repeat of their painful history on an even more cataclysmic scale.

All across Gaza, Palestinians in recent days have been loading up cars and donkey carts or setting out on foot to already overcrowded tent camps as Israel expands its offensive once again.

The war on Gaza has killed more than 35,000 Palestinians, according to local health officials, making it by far the deadliest round of fighting in the history of the long conflict.

About 1.7 million Palestinians, three-quarters of the besieged enclave’s population, have been forced to flee their homes, most of them multiple times. That is well more than twice the number that fled before and during the 1948 war.

Even if Palestinians are not expelled from Gaza en masse, many fear that they will never be able to return to their homes or that the destruction wreaked on the territory will make it impossible to live there. A recent United Nations estimate said it would take until 2040 to rebuild destroyed homes in the enclave.

Israel has unleashed one of the deadliest and most destructive military campaigns in recent history in Gaza, dropping 900kg (2,000-pound) bombs on densely populated areas. Entire neighbourhoods have been reduced to wastelands of rubble and ploughed-up roads, many littered with unexploded bombs.

The World Bank estimates that $18.5bn in damage has been inflicted, roughly equivalent to the gross domestic product of the entire Palestinian territory in 2022. And that was in January, in the early days of Israel’s devastating ground operations in Khan Younis and before its military went into Rafah.