This article is about the particular significance of the year 1918 to Wales and its people.

• Archdruid of the National Eisteddfod of Wales – Dyfed^[1]
• Lord Lieutenant of Anglesey – Sir Richard Henry Williams-Bulkeley, 12th Baronet
• Lord Lieutenant of Brecknockshire – Joseph Bailey, 2nd Baron Glanusk^[2]
• Lord Lieutenant of Caernarvonshire – John Ernest Greaves^[3]
• Lord Lieutenant of Cardiganshire – Herbert Davies-Evans^[4]
• Lord Lieutenant of Carmarthenshire – John Hinds
• Lord Lieutenant of Denbighshire – Lloyd Tyrell-Kenyon, 4th Baron Kenyon (from 24 January)
• Lord Lieutenant of Flintshire – Henry Gladstone, later Baron Gladstone^[5]
• Lord Lieutenant of Glamorgan – Robert Windsor-Clive, 1st Earl of Plymouth
• Lord Lieutenant of Merionethshire – Sir Osmond Williams, 1st Baronet^[6]
• Lord Lieutenant of Monmouthshire – Ivor Herbert, 1st Baron Treowen
• Lord Lieutenant of Montgomeryshire – Sir Herbert Williams-Wynn, 7th Baronet
• Lord Lieutenant of Pembrokeshire – John Philipps, 1st Viscount St Davids
• Lord Lieutenant of Radnorshire – Powlett Milbank^[7] (until 30 January); Arthur Walsh, 3rd Baron Ormathwaite (from 5 April)^[8]
• Bishop of Bangor – Watkin Williams^[9]
• Bishop of Llandaff – Joshua Pritchard Hughes^[10]
• Bishop of St Asaph – A. G. Edwards (later Archbishop of Wales)^[11]
• Bishop of St Davids – John Owen^[12]

• January – Coalowner, Liberal politician and Minister of Food Control David Alfred Thomas is created Viscount Rhondda; following his death on 3 July the title passes by special remainder to his daughter, the suffragette Margaret Mackworth.
• 26 January – An Irish steamship, the Cork, is torpedoed by a U-boat off Point Lynas in Anglesey. Twelve crew are killed.^[13][14]
• 29 January – The steamship Ethelinda is torpedoed by a U-boat off the Skerries. Twenty-six crew are killed.^[15]
• 4 February – The steamship Treveal is torpedoed by a U-boat off the Skerries. Thirty-three people are killed.^[16]
• 5 February – The steamship Mexico City is torpedoed by a U-boat off South Stack, Holyhead. Twenty-nine crew are killed.^[17]
• March
  • Miners' leader A. J. Cook is imprisoned for sedition under the Defence of the Realm Act 1914 for his public opposition to the war.^[18]
  • Submarines HMS R5 and HMS R6 are laid down at HM Dockyard Pembroke Dock; as with HMS L34 and L35 ordered later in the year, they will be cancelled in 1919 before completion.
• 2 March – The British submarine HMS H5 is rammed and sunk, having been mistaken for a U-boat, off Porthdinllaen. All twenty-six crew are killed.^[19]
• 7 March – The steamship Kenmare is torpedoed by a U-boat off the Skerries. Twenty-six crew are killed.^[20]
• 7 April – The steamship Boscastle is torpedoed by a U-boat off Strumble Head. Eighteen crew are killed.^[21]
• 21 April – The steamship Landonia is torpedoed by a U-boat off Strumble Head. Twenty-one crew are killed.^[22]
• 9 May – The steamships Baron Ailsa and Wileysike are torpedoed by a U-boat off Pembrokeshire. Fourteen crew are killed.^[23][24]
• 19 May – The German U-boat SM UB-119 is sunk, perhaps off Bardsey Island.^[25]
• 15 June – The steamship Strathnairn is torpedoed by a U-boat off Bishops and Clerks, Pembrokeshire. Twenty-one crew are killed.
• 22 August – The steamship Palmella is torpedoed by a U-boat off South Stack, Holyhead. Twenty-eight people are killed.^[26]
• 16 September – The steamship Serula is torpedoed by a U-boat off Strumble Head. Seventeen crew are killed.^[27]
• 18 September – The 38th (Welsh) Division is involved in the Battle of Epéhy.
• Autumn – Edward Thomas John (Liberal MP for East Denbighshire) defects to the Labour Party.
• 10 October – Three seamen are killed while returning to their ship by boat at Milford Haven.
• 14 October – The steamship Dundalk is torpedoed by a U-boat off the Skerries. Twenty-one crew are killed.^[28]
• 11 November – Armistice Day. Able Seaman Richard Morgan, serving aboard HMS Garland, is the last Welshman – and perhaps the last Briton – to be killed on active service in the First World War, in the course of which over 40,000 Welsh people have lost their lives.
• 15 November – The British submarine HMS H51 is launched at Pembroke Dock.
• 14 December – United Kingdom general election:
  • For the first time, a woman stands as a parliamentary candidate in Wales: Millicent Mackenzie^[29] stands unsuccessfully for the University of Wales, itself a new parliamentary seat (which is won by Herbert Lewis).
  • Home Rule for Wales is included as a policy in the manifesto of the Labour Party.
  • William Brace becomes Labour MP for Abertillery.
  • Alfred Onions becomes Labour MP for Caerphilly.
  • John Hugh Edwards becomes Liberal MP for Neath, his previous constituency of Mid Glamorganshire having been abolished.
  • Sir Robert Thomas, 1st Baronet, becomes Liberal MP for Wrexham.
  • David Sanders Davies becomes Liberal MP for Denbigh, standing against Edward Thomas John.
• December – The beginning of the 1918 flu pandemic which lasts into the following year and kills about 10,000 people in Wales.

• John Morris-Jones is knighted for his services to literature.^[30]
• August is fixed as the annual month of the National Eisteddfod of Wales.

• The Life Story of David Lloyd George (drama, not shown publicly until 1996)

• Baseball – First records of the Grange Gasworks Ladies team playing in Cardiff.

• 15 January – Billy Lucas, international footballer (died 1998)
• 6 March – Billy Hughes, footballer (died 1981)^[33]
• 7 May – Robert Davies, politician (died 1967)
• 9 May – Sir Kyffin Williams, artist (died 2006)^[34]
• 20 May – David Ormsby-Gore, 5th Baron Harlech (died 1985)^[35]
• 24 May – Jack Edwards, soldier and activist (died 2006)^[36]
• 28 May
  • James Eirian Davies, Methodist minister and poet (died 1998)^[37]
  • Mary Vaughan Jones, children's author (died 1983)^[38]
• 6 June – Susan Williams-Ellis, founder of Portmeirion Pottery (died 2007)^[39]
• 19 June – Ivor Griffiths, footballer (died 1993)
• 4 July – Tony Garrett, chairman of Imperial Tobacco (died 2017)
• 25 July – Dennis David, RAF ace (died 2000)^[40]
• 19 August – Dilys Elwyn Edwards, composer (died 2012)^[41]
• 19 September – Penelope Mortimer, writer (died 1999)^[42]
• 26 September – John Rankine, author (died 2013)
• 14 October – J. A. G. Griffith, lawyer and academic (died 2010)^[43]
• 19 October – Charles Evans, doctor and mountaineer (died 1995)^[44]
• 3 November – Glyn Williams, international footballer (died 2011)

• 30 January – Powlett Milbank, Lord Lieutenant of Radnorshire, 65^[45]
• 15 February – William Evans, judge, c.71
• 13 April
  • David Ffrangcon Davies, baritone, 62^[46]
  • Thomas Tannatt Pryce, VC recipient, 32 (killed in action)^[47]
• 3 July – David Alfred Thomas, 1st Viscount Rhondda, industrialist and politician, 62^[48]
• 13 September – Samuel Thomas Evans, MP, 59^[49]
• 21 September – Emily Charlotte Talbot, heiress, 78^[50]
• 27 September – Morfydd Llwyn Owen, composer, pianist and mezzo-soprano, 26 (medical complications)^[51]
• 15 October – William David Phillips, Wales international rugby player, 63
• 4 November – Wilfred Owen, poet from the Welsh borders, 25 (killed in action)^[52]
• 25 November – William Griffith, mining engineer who worked with Cecil Rhodes, 65^[53]
• 1 December
  • John Griffiths, artist, 81^[54]
  • Fred Perrett, Wales international rugby union player, 27 (died of wounds received in action)^[55]

• 1918 in Ireland