The lessons of 1917 had been applied, and a convoy system introduced since the outbreak of war, but the hard-pressed Navy could not escort convoys far into the Atlantic.
他们吸取了1917年的教训，自从战争爆发以来，就部署了护航措施，但经济拮据的海军，无法将商船队一直送进大西洋。
And this time, Germany had achieved in a few weeks what four years of machine-guns and mustard-gas had sought to prevent.
现在，德国在几星期内，就拿下了他们四年来一直设防的目标，
There were U-boat bases on the French Atlantic coast.
那就是法国在大西洋海岸的潜艇基地。
One factor alone weighed against the probability of German victory in the naval war.
要想阻止德军在海上的胜利，现在只有一根救命稻草了。
The U-boat force, so phenomenally successful in 1917, had not been built up in time for 1939.
像1917年那么强大的U艇力量，在1939年时还没有组建起来。
The bluffing over Danzig had meant that Hitler blundered into war while Danitz commanded less than sixty submarines.
但泽的虚张声势表明，希特勒是跌跌撞撞进入战争的，那时邓尼茨只有不到60艘潜艇。
Short-sighted strategy would keep the numbers at this level until late 1941.
缺乏深谋远虑的种种行为，使这个数量级一直保持到1941年末。
Although the sudden increase in U-boat successes after the collapse of France was alarming, it was not in itself a British disaster.
虽然U型潜艇在法国崩溃之后数量激增，令人恐惧，但这本身并不是英国的灾难。
To remain capable of a belligerent policy Britain required imports of thirty million tons a year.
为了保持战时政策正常施行，英国每年需要进口3000万吨物资，为此他们拥有3000万吨运载力。
A capital stock of thirteen million tons of shipping was available for this purpose.
为此他们拥有3000万吨运载力。
During the year after June 1940, U-boat sinkings were to deplete that stock by an average of 200,000 tons a month.
1940年6月之后的一年间，潜艇的攻击平均每月会造成近20万吨运力的损失，
This loss in capacity could just about be replaced.
这个损失刚好能够按时补充。