Complex sentence: On 14 May 1948-day Israel declared independence, almost all British forces still in Palestine had withdrawn into a small enclave in Haifa, at its port, which was established to ensure the withdrawal of the remaining British personnel and equipment in Palestine.
Split into simpler sentences: On 14 May 1948-day Israel declared independence, the British had by then almost completely abandoned Palestine. Nearly all British forces still in Palestine were stationed Haifa, in an enclave in the city's port area, which was established to ensure the withdrawal of the remaining British personnel and equipment in Palestine.