Definition of "manfully"

[…] Apollyon wounded him in his head, his hand and foot; this made Chriſtian give a little back: Apollyon therefore followed his work amain, and Chriſtian again took courage, and reſiſted as manfully as he could.

1678, John Bunyan, The Pilgrim’s Progress from This World, to That which is to Come: […], London: […] Nath[aniel] Ponder […]; reprinted in The Pilgrim’s Progress (The Noel Douglas Replicas), London: Noel Douglas, […], 1928, page 72

She manfully struggled on, however - womanfully would perhaps be a stronger and more appropriate word. She had to calculate not only how to play her own hand correctly, but she had to calculate on her partner's probable errors.

1859, Anthony Trollope, The Bertrams, page 264

One (ant) struggled manfully by with a dead spider five times as big as itself in its arms.

1876, Mark Twain [pseudonym; Samuel Langhorne Clemens], The Adventures of Tom Sawyer, Hartford, Conn.: The American Publishing Company

"Whilst he was sawing the beam, however, a fire broke out among the debris around him, and though he persevered most manfully, and continued until he was himself badly scorched, it was impossible for him to save Beale, who probably died from suffocation."

1925 July – 1926 May, A[rthur] Conan Doyle, “(please specify the chapter number)”, in The Land of Mist (eBook no. 0601351h.html), Australia: Project Gutenberg Australia, published April 2019

YOUR SON WAS SERIOUSLY WOUNDED WHEN SHOT DOWN IN HANOI BUT HAS MADE FINE RECOVERY AND NOW, ACCORDING THIS GROUP, LOOKS "QUITE WELL." HE HAS BEEN EVERYTHING YOU WANT YOUR SON TO BE AND HAS STOOD UP MANFULLY AGAINST ALL EFFORTS TO PERSUADE HIM TO UTTER TRAITOROUS STATEMENTS.

1999, John McCain, Faith of My Fathers‎, New York: Random House, page 285