Wikipedia has a more complete version than the one in the DigiTrad:

THE RED FLAG
(Jim Connell)

    The people's flag is deepest red,
    It shrouded oft our martyred dead,
    And ere their limbs grew stiff and cold,
    Their hearts' blood dyed its every fold.

       Then raise the scarlet standard high. (chorus)
       Within its shade we live and die,
       Though cowards flinch and traitors sneer,
       We'll keep the red flag flying here.

    Look round, the Frenchman loves its blaze,
    The sturdy German chants its praise,
    In Moscow's vaults its hymns were sung
    Chicago swells the surging throng.

       (chorus)

    It waved above our infant might,
    When all ahead seemed dark as night;
    It witnessed many a deed and vow,
    We must not change its colour now.

       (chorus)

    It well recalls the triumphs past,
    It gives the hope of peace at last;
    The banner bright, the symbol plain,
    Of human right and human gain.

       (chorus)

    It suits today the weak and base,
    Whose minds are fixed on pelf and place
    To cringe before the rich man's frown,
    And haul the sacred emblem down.

       (chorus)

    With head uncovered swear we all
    To bear it onward till we fall;
    Come dungeons dark or gallows grim,
    This song shall be our parting hymn.

The author's name is Connell, not O'Connell; the correct date is 1889, not 1899.