In a cheerless manner:
— In August 1914, there was a dismally sentimental little dinner, when the French, German, Austrian and Belgian members of the committee drank together to the peace of the future.

synonym: drearily.

In a dreadful manner:
— As he looks at the mess he has left behind he must wonder how the Brits so often managed to succeed in the kind of situation where he has so dismally failed.

synonym: dreadfully.