fateful

1. ADJ If an action or a time when something happened is described as fateful, it is considered to have an important, and often very bad, effect on future events. 有重大影响的 (尤指产生负面结果的)

It was a fateful decision, one which was to break the Government. 那是一项重大的决定，一个将使政府垮台的决定。