In the meantime, some of the scientists who had been Haber's counterparts and competitors in England during World War I now helped him and others to leave Germany. Brigadier Harold Hartley, Sir William Jackson Pope and Frederick G. Donnan arranged for Haber to be officially invited to Cambridge, England. There, with his assistant Joseph Joshua Weiss, Haber lived and worked for a few months. Scientists such as Ernest Rutherford were less forgiving of Haber's involvement in poison gas warfare: Rutherford pointedly refused to shake hands with him.