The 1915–16 season would have been Manchester United's 24th season in the Football League and ninth in the First Division.

With the start of the First World War, all Football League football was cancelled. In its place were formed War Leagues, based on geographical lines rather than based on previous league placement. Manchester United contested the Lancashire Section in the Principal Tournament, and the Southern Division of the Lancashire Section in the Subsidiary Tournament. However, none of these were considered to be competitive football, and thus their records are not recognised by the Football League.

Lancashire Section Principal Tournament DateOpponentsH / AResultF–AScorersAttendance4 September 1915Oldham AthleticA2–3Halligan, Wilson11 September 1915EvertonH2–4Wilson (2)18 September 1915Bolton WanderersA5–3West (2), Woodcock (2), A. Davies25 September 1915Manchester CityH1–1Halligan2 October 1915StokeA0–09 October 1915BurnleyH3–7D. Davies, Wilson, Woodcock16 October 1915Preston North EndA0–023 October 1915Stockport CountyH3–0Halligan, Hughes, Woodcock30 October 1915LiverpoolA2–0West, Wilson6 November 1915BuryH1–1Woodcock13 November 1915RochdaleH2–0A. Davies, Gipps20 November 1915BlackpoolA1–5Woodcock27 November 1915Southport CentralH0–04 December 1915Oldham AthleticH2–0Anderson, Halligan11 December 1915EvertonA0–218 December 1915Bolton WanderersH1–0Bracegirdle25 December 1915Manchester CityA1–2Halligan1 January 1916StokeH1–2Woodcock8 January 1916BurnleyA4–7Travis (4)15 January 1916Preston North EndH4–0Woodcock (2), Hughes, Halligan22 January 1916Stockport CountyA1–3Woodcock29 January 1916LiverpoolH1–1Cookson5 February 1916BuryA1–2Travis12 February 1916RochdaleA2–2Halligan, Woodcock19 February 1916BlackpoolH1–1Woodcock26 February 1916Southport CentralA0–5

Lancashire Section Subsidiary Tournament Southern Division DateOpponentsH / AResultF–AScorersAttendance4 March 1916EvertonH0–211 March 1916Oldham AthleticA0–118 March 1916LiverpoolH0–025 March 1916Manchester CityH0–21 April 1916Stockport CountyA3–5Campey (2), Winterburn8 April 1916EvertonA1–3Forster15 April 1916Oldham AthleticH3–0Crossley, Halligan, Knowles21 April 1916Stockport CountyH3–2Crossley, Halligan, Woodcock22 April 1916LiverpoolA1–7Woodcock29 April 1916Manchester CityA1–2Crossley

References