Yes, the President made a grievous personal error to the detriment of his family.
Unless someone has made a grievous error, this is November.
It also makes the grievous error of beginning with the general and leaving the particular to fend for itself.
It was enough to know that they died screaming, conscious of their grievous error at the last.
But we can prevent a grievous error from being done.
It was a grievous error for this news to be released.
"I think you have made a grievous error," she said.
The next call was simply Detroit's fault, a grievous error at a terrible time.
"We made a grievous error" in the wording of the letter, he said.
I may have made a grievous error, and thereby cost myself the victory.