A hundred years ago a British foreign secretary penned arguably the most contentious 67 words ever written.
Arthur Balfour was writing to Lord Walter Rothschild, a leader of the British Jewish community.
His government, he said, viewed “with favour the establishment in Palestine of a national home for the Jewish people” and would use its “best endeavours to facilitate the achievement of this object”.
However, it went on, “nothing shall be done which may prejudice the civil and religious rights of existing non-Jewish communities in Palestine, or the rights and political status enjoyed by Jews in any other country.”
The letter, which was soon made public, is blamed for launching the process that ended up with the Israeli-Palestinian conflict.
Israelis have revered the name Balfour with streets and schools. To this day his declaration is regarded as one justification for the existence of the Jewish state.
Palestinians on the other hand blame it for much of their suffering because of the conflict they say it caused. They and their supporters demand Britain acknowledge its part in their ordeal.
British Prime Minister Theresa May will say the declaration “demands of us today a renewed response to support a lasting peace that is in the interests of both Israelis and Palestinians.”
But many observers believe the window of opportunity for that lasting peace is closing or has in fact closed.
The Balfour Declaration is significant for what it partly led to and because of what it said.
It strengthened the resolve of Zionists seeking to create a Jewish homeland out of a chunk of territory that was part of the dying Ottoman Empire.
The land was called Palestine and Britain had responsibility for it after the First World War.
Jews had already bought a lot of the land there, especially around Jerusalem, and continued to do so.
Some organised themselves to use terrorist methods to fight for a Jewish state, blowing up hotels and attacking both military and civilian targets.
Arabs who had lived there for generations and would later call themselves Palestinians opposed the creation of a Jewish state.
In 1947 the UN tried to mediate between them proposing the partition of Palestine into Jewish and Arab states. Member states voted in favour 33 to 13, with 10 abstentions.
The Balfour Declaration formed one of the principles of British policy in the Levant.
It is also quoted to this day as one of the justifications for the State of Israel, even if Israelis have routinely disregarded and ignored many pronouncements of British government officials when it has suited them since.
The Israeli Knesset will hold a special celebratory meeting to mark the anniversary.
Some Israeli Arab lawmakers say they will boycott celebrations, while Palestinian leader Mahmoud Abbas has urged the British Government to declare the declaration a mistake.
“The creation of a homeland for one people resulted in the dispossession and continuing persecution another” he wrote this week, “now a deep imbalance between occupier and occupied”.