1901–1939

• 1906 – Municipal Market Hall and Copernicanum building completed.
• 1908 – Population: 57,696.^[4]
• 1919 – Bydgoszcz restored to Poland after the country regained independence.
• 1920
  • 24 January: 62th Infantry Regiment of the Polish Army stationed in Bydgoszcz.^[5]
  • 14 May: Polonia Bydgoszcz football club (future multi-sports club) founded.
  • 69th Infantry Regiment of the Polish Army stationed in Bydgoszcz.^[6]
• 1921 – 1 November: 62th Infantry Regiment of the Polish Army relocated from Gniezno to Bydgoszcz.^[7]
• 1923 – Regional Museum in Bydgoszcz founded.
• 1929 – City hosts the 1929 European Rowing Championships.
• 1930 – Botanic Garden of Casimir the Great University founded as the Municipal Botanic Garden.

World War II (1939–1945)

German execution of Polish hostages at the Market Square in 1939

• 1939
  • September: City is occupied by Nazi Germany.
  • 3 September: German diversion, resulting in Polish-German skirmishes, which were referred to as the Bloody Sunday by propaganda of Nazi Germany to serve as an excuse for planned German massacres of Polish residents.
  • 3–10 September: Germans massacred 192 Poles in the city.^[8]
  • September: Einsatzgruppe IV, Einsatzkommando 16 and SS-Totenkopf-Standarte "Brandenburg" Nazi paramilitary death squads entered the city.^[9]
  • 10 September: Germans carried out mass searches of houses throughout the city.^[8]
  • 24 September: Appointed German Kreisleiter called local Polish city officials to a supposed formal meeting in the city hall, from where they were taken to a nearby forest and exterminated.^[10] He also ordered the execution of their family members to "avoid creating martyrs".^[10]
  • September: Nazi prison and forced labour camp established by the Germans at Wały Jagiellońskie Street.^[11]
  • 22, 29 September: Massacres of 250 Polish activists previously imprisoned in a local Selbstschutz prison during the Intelligenzaktion.^[8]
  • 30 September: Over 3,000 Poles imprisoned by the Germans in the city as of 30 September.^[12]
  • Early October: Further mass arrests of over 2,000 Poles.^[12]
  • 18–20 October: Further mass arrests of nearly 1,500 Poles, incl. activists and teachers, carried out by the German police, Einsatzkommando 16 and Selbstschutz.^[12]
  • October–November: Large massacres of Poles and Jews carried out by the Germans in the Valley of Death.
  • 1 November: City unilaterally annexed by Germany.^[13]
  • 11 November: Further mass arrests of 3,800 Poles carried out by the German police and Selbstschutz.^[14]
  • 11 November: Public execution of pre-war Polish mayor Leon Barciszewski by the Germans.^[15]
  • 17 November: Commander of the local SD-EK unit declared there was no more Polish intelligentsia capable of resistance in the city.^[15]
  • November: Einsatzgruppen-operated penal camp established in the Jachcice district.^[16]
  • November–December: First expulsions of Poles from Bydgoszcz.^[17]
  • Massacres of over 1,400 Poles from Bydgoszcz, incl. teachers, activists, priests, old people, boy and girl scouts, gymnasium students, and children as young as 12, in the nearby village of Tryszczyn.^[18][19]
  • Bromberg Dynamit Nobel AG Factory founded.
• 1940
  • January: Poles from Bydgoszcz among the victims of a massacre perpetrated by the Selbstschutz in Jastrzębie.^[20]
  • May, September–October: Further expulsions of over 3,000 Poles from Bydgoszcz.^[21]
• 1941
  • January–February: Further expulsions of some 4,200 Poles from Bydgoszcz.^[22]
  • 4 February: First mass transport of 524 Poles sent from Bydgoszcz to the Potulice concentration camp.^[23]
  • May: Forced labour camp established by the Germans in the Smukała Dolna district.^[24]
  • September: Transit camp for expelled Poles from the region established in Smukała.^[25]

Forced labour of Polish prisoners in 1942

• 1943
  • March: Rescue of some kidnapped Polish children from the Zamość region by local Poles.^[26]
  • The local Polish resistance movement sheltered British prisoners of war who escaped from the German Stalag XX-A POW camp, and facilitated their escapes to neutral Sweden.^[27]
• 1944
  • 24 June: Explosion at the Dynamit Nobel AG Factory kills 15 people.^[28]
  • 12 September: Bromberg-Ost subcamp of the Stutthof concentration camp established by the Germans.
• 1945 – End of German occupation, Bydgoszcz restored to Poland.

1945–2000

• 1949 – Polish Theatre in Bydgoszcz completed.
• 1951 – Bydgoszcz University of Science and Technology founded.
• 1955 – Polonia Bydgoszcz wins its first Team Speedway Polish Championship.
• 1969 – Kazimierz Wielki University in Bydgoszcz founded.
• 1978 – Andrzej Szwalbe Collection of Historical Pianos founded by Andrzej Szwalbe.^[29]
• 1981 – Bydgoszcz events.
• 1984 – Nicolaus Copernicus University Ludwik Rydygier Collegium Medicum in Bydgoszcz founded.
• 1990 – First apartment block of the Independence Estate.
• 1993 – Pałac Bydgoszcz wins its first Polish women's volleyball championship.
• 2000 – Andrzej Szwalbe Collection of Historical Pianos relocated from Bydgoszcz to the Palaces and park ensemble in Ostromecko.