The following list of events is largely based on publications by William Gates with additional material from a range of historians.
1900 Aug 24 - The construction of St. Swithun's church commenced.
1900 - HMS Powerful returned from South Africa. The Mayor gave a banquet for the Captain and crew.
1900 December 31 - The Tramway undertaking transferred to the Corporation, the price arranged by arbitration being £195,633.
1901 Jan 28 - Edward VII proclaimed King on the steps of the Town Hall.
1901 March 9 - The Hampshire Regiment Drill Hall in Stanhope Road opened.
1901 March 31 - The census showed the population to bo 189,160.
1901 July 24 - Heavy rain caused flooding in Southsea.
1901 Sept 29 - The death of Robert East, compiler of "Extracts from the Portsmouth Records".
1901 Dec 8 - Queens Hotel destroyed by fire.
1902 May 21 - Foundation stone for St Matthew's church laid.
1903 June 19 - Consecration of St. Margaret's, Eastney.
1903 July 7 - Statue of Queen Victoria unveiled in Town Hall Square.
1903 July 7 - Squadron of American warships at Spithead.
1903 - Naval Barracks in Anglesea Road opened.
1904 - Captain Scott and the crew of the Discovery given a banquet in the Guildhall.
1904 March 18 - The Submarine A1 was struck by the Berwick Castle whilst submerged off the Nab. Two Officers and nine men died.
1904 July 19 - South Parade Pier partially destroyed by fire.
1904 July 22 - Charles Dickens' birthplace in Commercial Road opened as a museum.
1904 July 22 - Foundation stone of New Municipal College laid.
1904 - The boundaries of Portsmouth extended to cover the whole of Portsea Island, Drayton and Wymering.
1905 June 5 - Naval reception for the King of Spain.
1906 Jan 10 - Death of Sir William Pink, five times Mayor.
1906 Feb 12 - The battleship Dreadnought launched by King Edward VII.
1906 Sept 12 - The Carnegie Library in Fratton Road opened.
1906 October 24 - The Camber Bridge was re-opened.
1906 November - Serious rioting at the Naval Barracks.
1907 June 27 - The opening of Alexandra Park.
1907 Nov 11 - The German Emperor with a squadron of warships at Portsmouth.
1908 April 26 - The Gladiator sunk off Yarmouth IoW after collision with an Atlantic liner.
1908 May 9 - Death of Timothy White, founder of retail chain.
1908 July 13 - Copnor Bridge opened, replacing a dangerous level crossing.
1908 Sept 8 - New Municipal College opened by the Mayor Ferdinand G. Foster.
1909 May 18 - Death of George Meredith, author.
1909 Sept 30 - Launch of H.M.S. Neptune, an improved Dreadnought.
1909 Nov 9 - Death of Sir John Baker, twice mayor and former MP.
1910 - Work began on the demolition of the worst of the slums in Portsea.
1911 June 24 - Coronation Naval Review at Spithead.
1911 - The Council purchase large areas of Milton and Great Salterns.
1911 - A Labout Exchange opened in Lake Road with 60 staff.
1912 Feb 2 - Submarine A3 sank after collision with the loss of four officers and ten crew.
1912 May 8 - New park at Baffins opened.
1912 July 9 - Naval Review at Spithead with 223 warships.
1912 Oct 12 - HMS Iron Duke launched.
1913 Oct 16 - HMS Queen Elizabeth, a super-Dreadnought, launched.
1913 Dec 20 - The Semaphore Tower in the Dockyard destroyed by fire. Two night watchmen died.
1913 April 21 - William Saunders, local historian and curator of Portsmouth Museum died.
1914 Sept - Recruitment amongst local volunteers began.
1915 April 15 - Portsmouth's Own 1st Battalion of volunteer recruits sets off for training.
1915 March 12 - Death of Sir George Turner, first Medical Officer of Health.
1916 April 29 - Portsmouth becomes the first town in the country equipped with an automatic telephone exchange.
1916 May 31 - The Battle of Jutland.
1916 June - The loss of HMS Hampshire with Lord Kitchener on board.
1917 - Portsmouth raises £4,027,000 for the war effort.
1917 - Sergeant James Ockendon wins the Victoria Cross.
1918 June - The Mental Asylum at Milton was handed over to the Americans for use as a hospital.
1918 Oct 2 - The death of Agnes Weston, founder of the Royal Sailors Rest.
1919 - Partial demolition of Hilsea Lines.
1921 Jan 20 - Submarine K5 lost with all hands, including 33 men from Portsmouth.
1921 - The Council decide to remove the lines of the Southsea Railway and release the land for housing.
1921 Oct 19 - The Cenotaph in Town Hall Square unveiled by the Duke of Connaught.
1921 Nov 26 - The death of Miss Sarah Robinson, founder of the Soldiers Institute.
1922 Jan 12 - HMS Victory towed on it's last journey into dry dock.
1922 - Southsea Common purchased from the War Office by the Town Council.
1923 - Gunwharf transformed into a training establishment for officers and men in torpedo warfare and renamed HMS Vernon.
1923 - The house of John Pounds in Highbury Street purchased for the town.
1924 - The Naval Memorial of the Great War on Southsea Common unveiled.
1925 May 28 - Northern Road, Cosham opened.
1925 June - The Royal Agricultural Show attracts 79,157 visitors.
1925 Nov 12 - Submarine M1 lost. She had a crew of 68 officers and men.
1926 - Portsmouth designated a city.
1926 July 14 - Golf Course at Great Salterns opened.
1926 March 15 - Death of Sir Philip Watts, designer of the Dreadnought.
1927 July 14 - The new Portsbridge opened to replace the old swing bridge.
See also the Chronology of Events for the periods
500-1499 | 1500-1599 | 1600-1699 | 1700-1799 | 1800-1849 | 1850-1899