They had many wars (and military campains) against the Ottomans, including with Ottoman backed Sharif of Makkah, Sharif of Makkah betrayed the Ottomans right at the end 1916 when he thought he will be made the Khaleef by Britain, but instead Britain backed Al Saud for SA and Sharif kids for Jordan/Iraq. Al Saud would never have been given power without British backing. Anyways this is a long history.
The first Ottoman-Najdi wars are that fought between the Ottoman state against the first Wahabi state, the Emirate of Diriyyah.
en.wikipedia.org
It was won by the Ottomans in 1818, but then the successor state of the Emirate, the Emirate of Najd finally expelled Ottoman Egypt's eyalet troops out from parts of the peninsula somewhere in 1824. It ruled until 1891 when it was lost to the Rashidis of Jabal Shammar.
The Rashidis of Jabal Shammar lose again to the Saudis in the war for Qassim region in 1907.
The Third Saudi state (the Emirate of Riyads) was at war with the Ottomans to capture Al-Hassa, this time however the Ottomans are backed by the Brits. This happened in 1913.
Then a year later WW1 erupted, and the British using fostered Arab nationalism began to arm Arab nationalist, one particular is the Kingdom of Hejaz with Sharif Ali as their king.
en.wikipedia.org
The Hejazi king however didn't directly participate out of love for the Zionists
His kingdom also cease to exist just a few years later when the Ikhwan (not the MB one) of the Saudi clan defeated him in 1925.
So yeah, the Saudis didn't actually betray the Ottomans in WW1.
If they're at war with the Ottomans, they did that on their own or against a British backed Ottoman state
My point is a deal was done for the establishment of the zionist state, in order for these kingdoms to be established and protected, and this is proven today when these same kingdoms are betraying the Palestinians, on top openly calling for a zionist state to be establishment. Why Iranian influence or Turk Influence is not acceptable but they're fine with Israel. Lastly the zionist made offers to Ottoman Khaleef to allow the establishment of Israel but he rejected the offer with a famous reply
The idea was always to divide the Muslims ummah into states with fixed borders, Westaphalian style state. Many Muslims fell to the trap like the Sharif of Mecca, Sharif Ali.
But it was no mean that the past Saudis actually betray the Ottoman state so that a zionist country could be built on top of Muslim land
We can tell from here, the Ottomans had to go so Israel can be established. The rulers who came after them all sold Islam for thrones.
We can tell that nationalism has been catastrophic and failure.
To win, Muslims must throw ideas like secularism, nationalism, and those -isms from Europe and back to the religion that Muhammad Taught his disciples that had transformed Arabs from a loser nation into one the greatest nations on earth.