120 Days

Invasion was coming. The Allied chiefs had been picked. The London press reported millions of U.S. soldiers pouring into Britain ("straphanging across the Atlantic," one newspaper called it). The fact that British railways were busy with a "gigantic" shift of men and supplies was public property.

D-Day was still the war's tightest secret. But this much is certain: it will be the earliest day on which 1) the problems of logistics and planning have been licked; 2) all-important weather is friendly. Quite possibly, it may be a day among the next 120.

General Weather. Fog, rain, snow, tide, wind and moon will have much to do with the timing. Cold, rainy, foggy January and February are poor invasion months. March is better, though its winds can play havoc with shallow-bottomed craft. Treacherous, unpredictable Channel fogs are no worse in March than in any other month.

At large harbors, such as Le Havre or Cherbourg, the tide is relatively unimportant; it is crucial on long, low beaches on which invaders can land only at high tide. Extreme tides coincide with full moon. The western wall of Hitler's Europe will see the full moon on Jan. 10, Feb. 9, March 10, April 8.

Soldiers and airmen like bright, moonlit nights; sailors detest them. The Navy's ideal for an invasion is a dark night, with a light breeze and fair visibility. Next best is a full moon, shrouded with clouds so that just enough light filters through to maneuver ships & men. But the sailors especially hate fog; though it provides cover against the enemy, it hampers naval gunnery, endangers crowded shipping, grounds friendly airmen.

Pea-soup fog might be catastrophic to invasion barges, compelled to navigate blindly. It would also rob the invaders of a chance to exploit initial advantage, help the enemy to shift his troops without air hindrance.

U.S. and British airmen proved last week that in Europe's winter they can find a succession of days when invasion flying is feasible. But those days are hard to predict. For all its weather data, the entire U.S. Army in the European theater now looks to its Air Forces.

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