Complex sentence: Debs had joined the Brotherhood of Locomotive Firemen (BLF) in February 1875 and became active in this fraternal benefit organization; in 1877 he served as a delegate of the Terre Haute lodge to the organization's national convention.
Split into simpler sentences: Debs had joined the Brotherhood of Locomotive Firemen (BLF) in February 1875 and became active in this fraternal benefit organization. In 1877 he served as a delegate of the Terre Haute lodge to the organization's national convention.