They changed the way we fought war--caused us to back away from trench warfare.

以往的发明也曾改变过我们进行战争的方式，使我们远离了堑壕战。

They changed the way we fought war -- caused us to back away from trench warfare.

以往的发明也曾改变过我们进行战争的方式,使我们远离了堑壕战.

So when the First World War broke out, the result was the trench warfare that lasted longer than anybody had expected.

于是当第一次世界大战爆发时，结果便是持续时间超乎任何人想象的壕沟战。