The Overlord planners for the invasion of Europe in 1944 specified suitable weather (wind, cloud, tidal and moon conditions) for the assault landing; with only a few days in each month suitable. So in May and June frequent pre-assault meetings were held at Southwick House in Hampshire near Portsmouth by Eisenhower with Group Captain James Stagg of the RAF, the Chief Meteorological Officer, SHAEF, his deputy Colonel Donald Yates of the USAAF, and his three two-man teams of meteorologists. Stagg was a "dour but canny Scot.. " He had been given the rank of group captain in the RAF "to lend him the necessary authority in a military milieu unused to outsiders". The senior commanders were General Bernard Montgomery, Admiral Sir Bertram Ramsay and Air Marshal Sir Trafford Leigh-Mallory, plus Eisenhower's deputy, Air Marshall Arthur Tedder, his chief of staff Walter Bedell Smith and his deputy chief of Staff Major General Harold R. Bull.