The difficult conditions on the ships demanded a high level of discipline. The people on board the ships were often split into units, led by commanders. In addition to having a daily roll call and the distribution of food and water (usually very little of either), organized talks were held to provide information regarding the actual arrival in Palestine. One of the largest ships was the "Sakaria", with 2,300 passengers, which equalled about 0.5% of the Jewish population in Palestine. The first vessel arrived on April 13, 1937, and the last on February 13, 1940. All told, about 18,000 Jews immigrated to Palestine with the help of the Revisionist organizations and private initiatives by other Revisionists. Most were not caught by the British.