Pan ddechreuodd y Rhyfel Byd Cyntaf, recriwtiwyd nifer fawr o swyddogion Heddlu Morgannwg a heddluoedd bwrdeistrefi’r De i’r lluoedd arfog. Yn sgîl hynny, roedd llawer o swyddi gwag yn yr heddlu, ac ymrestrodd rhai o’r rheini nad oedd wedi ymuno â’r lluoedd arfog i ymuno â’r heddlu. Adlewyrchir hynny yn adroddiadau papur newydd y cyfnod, a gedwir ymhlith y llyfrau torion papur newydd a gasglwyd gan Heddlu Bwrdeistref Caerdydd:
‘Many citizens have enrolled themselves as special constables at Cardiff and have signified their intention of rendering service gratis’; ‘355 special constables recruited’. Heddlu Bwrdeistref Caerdydd, torion papur newydd (DCONC/5/46)
‘The number of special constables in Cardiff is around 1100 and 1200. There are 228 vacancies due to many who have joined the colours’. Heddlu Bwrdeistref Caerdydd, torion papur newydd (DCONC/5/52)
Gan fod cymaint o ddynion wedi ymuno â’r lluoedd arfog, roedd yn gyfle i fenywod gymryd rhan ym mhatrolau’r heddlu, yn ogystal â’r gwaith roeddent yn ei gyflawni eisoes o ran goruchwylio, chwilio a hebrwng menywod a phlant yn y ddalfa. Mae cofnodion Cydbwyllgor Sefydlog [Yr Heddlu] Cyngor Sir Forgannwg yn nodi’r canlynol:

‘By permission of the Chairman I have made small temporary advances of 10s. per week to the wives of the reservists recalled to the Colours, for their immediate requirements. Seven of these are stationed in County Police cottages, which must be kept at the disposal of the Police’. Cydbwyllgor Sefydlog [Yr Heddlu] Cyngor Sir Forgannwg, cofnodion (GC/SJ/4/2)
Roedd llawer o’r heddweision benywaidd yn wragedd dynion a oedd yn gwasanaethu yn y lluoedd arfog. Fodd bynnag, er eu bod yn cael eu gweld y tu allan i orsaf yr heddlu yn amlach nag o’r blaen, roedd patrolau’r swyddogion heddlu benywaidd fel arfer yn canolbwyntio ar atal menywod rhag ‘mynd ar gyfeiliorn’, yn foesol ac yn llythrennol, tra bod heddweision gwrywaidd yn cyflawni dyletswyddau eraill.
Roedd angen i’r dynion a oedd yn ymuno â’r heddlu fod yn ymwybodol y gallent gael eu galw i wasanaethu yn y lluoedd arfog rywbryd yn y dyfodol:
‘…the only men belonging to the special police who can regard themselves as exempt from military services are those of 35 and over’. Heddlu Bwrdeistref Caerdydd, torion papur newydd (DCONC/5/52)
Amcangyfrifwyd bod tua 60-70% o’r dynion a ymrestrodd fel cwnstabliaid arbennig yn y De ar ddechrau’r rhyfel wedi’u cynnwys o dan ddarpariaethau’r gorchymyn uchod.
Yn anochel, gwnaeth llawer o’r cwnstabliaid hynny a oedd yn gwasanaethu yn y lluoedd arfog yr aberth eithaf dros y wlad:
‘The Head Constable reported that Constable Camfield was killed in action between 14-16 Sep at Soupir, France’. Cyngor Bwrdeistref Caerdydd, cofnodion (BC/C/6/49)
‘The Head Constable reported that the following members of the Force had been killed in action, namely, Constable Bert Clements, 34c, Constable Frank Willis, 43c, and Constable Frank Ford, 17b’; ‘The Head Constable reported the deaths of Constable Thomas Lemuel Jones and Constable Walter John Twining. PC Jones was a Reservist of the Grenadier Guards, and PC Twining on 6 Sep rejoined his old Regiment the 10th Hussars’. Cyngor Bwrdeistref Caerdydd, cofnodion (BC/C/6/50)
‘The Head Constable reported the death of Lance-Corporal HJ Fisher, of the Welsh Guards, killed in action in France on 16 Sep’. Cyngor Bwrdeistref Caerdydd, cofnodion (BC/C/6/53)
‘The Head Constable reported the death of Probationer Constable Milton Horace Wood, a Reservist of the RAMC, who married after leaving the Force, and left a widow and child behind him’. Cyngor Bwrdeistref Caerdydd, cofnodion (BC/C/6/55)
‘Welsh Guardsman George Lock ex Cardiff Police killed in action’. Heddlu Bwrdeistref Caerdydd, torion papur newydd (DCONC/5/51)
Cafodd llawer ohonynt eu hanafu, felly nid oeddent yn ffit i wasanaethu gyda’r heddlu ar ôl dychwelyd o’r lluoedd arfog:
‘25 of our men have been discharged from the Army for various reasons. Of these, five have not rejoined the Force, four have rejoined the Force and then left on account of their health or to obtain more remunerative employment, and 16 are still serving in the Force’. Cydbwyllgor Sefydlog [Yr Heddlu] Cyngor Sir Forgannwg, cofnodion (GC/SJ/4/2)
Wrth i’r rhyfel fynd yn ei flaen, roedd nifer cynyddol o Heddweision yn gwasanaethu yn y lluoedd arfog, ac er gwaethaf recriwtio sifiliaid fel y nodwyd uchod, roedd prinder y cwnstabliaid yn peri pryder i’r heddlu:
‘The Military Authorities having now further depleted the Police Force beyond the 250 which the Committee deemed indispensable for their general duties (which are very heavily increased), the attention of the Chief Constable was called to the resolution of the March 1917 meeting of the Committee as to the Police not undertaking voluntary work for the Military Authorities, which they expect will be carried out’. Cydbwyllgor Sefydlog [Yr Heddlu] Cyngor Sir Forgannwg, cofnodion (GC/SJ/2/2)
Drwy gydol y Rhyfel, roedd disgwyl i’r Heddlu barhau i gyflawni eu dyletswyddau o orfodi’r gyfraith yn y meysydd yr oeddent yn gyfrifol amdanynt. Daeth rhai cyfreithiau newydd i rym yn sgîl y rhyfel yn benodol , yn bennaf yn sgîl Deddf Amddiffyn y Deyrnas 1914; un enghraifft oedd gorfod pylu goleuadau gyda’r nos:
‘…the Head Constable communicated with those Lighting Authorities, Companies or persons within the City whom he may think necessary, requested them to take steps gradually to diminish their lights from the hours of 10pm to 12 midnight, after which latter hour all prominent lights must be extinguished or subdued in such a manner as not to be visible from above’. Cyngor Bwrdeistref Caerdydd, cofnodion (BC/C/6/49)
Ymhlith yr enghreifftiau eraill roedd gwaharddiadau ar werthu alcohol, carcharu heb dreial, sensoriaeth o ran geiriau argraffedig a geiriau llafar a chyfyngiadau o ran symudiad estroniaid; gan gynnwys ffoaduriaid o Wlad Belg neu gyn-drigolion yr Almaen ac Awstria. Arweiniodd amheuon y cyhoedd Prydeinig ynghylch cyn-drigolion yr Almaen at derfysgoedd y bu’n rhaid i’r Heddlu fynd i’r afael â nhw:
‘On the 15th May 1915, anti-German riots took place at Neath, and some looting occurred. The Neath Police were overpowered, and Supt. Ben. Evans, of the “D” or Neath Division of the County Police, sent three Inspectors, three Sergeants, four acting sergeants, and 12 Constables to their assistance. With the Assistance of this Force the riot was quelled’. Cydbwyllgor Sefydlog [Yr Heddlu] Cyngor Sir Forgannwg, cofnodion (GC/SJ/4/2)
Roedd gwrthdaro rhwng heddychwyr a chefnogwyr y rhyfel yn broblem arall i’r Heddlu. Arweiniodd y gwrthdaro hwn at olygfeydd rhyfeddol ar un achlysur mewn neuadd yng Nghaerdydd:
‘Scenes were witnessed in Cardiff when protesters against the peace policy of the National Council for Civil Liberties stormed the Cory Hall and forced the delegates to abandon their meeting. A meeting had been held previously to take steps to prevent the holding of the conference. A procession was arranged and when they arrived at the Hall, where they were unopposed by the police but met resistance, but were able to gain entrance and soon the delegates lead by Mr Ramsay Macdonald MP beat a retreat. There were no arrests’. Heddlu Bwrdeistref Caerdydd, torion papur newydd (DCONC/5/52)
Ar ôl diwedd y rhyfel, dechreuodd yr Heddweision fu’n gwasanaethu yn y lluoedd arfog ddychwelyd i’w gwaith blaenorol, gan gymryd lle’r gwirfoddolwyr:
‘The strength of the Force is 627, being 101 below authorised strength of 728. There are also 74 members with the Private companies, including five Weights and Measures Inspectors. I herewith append a schedule showing the number of men who have returned to the Force from Active Service, and their state of health: No. of men returned unfit for further Military Service 57. No. of men returned to the Force upon demobilisation 198. No. of men passed as ‘Fit for Police duty’ and now serving in the Force 169. No. of men placed ‘Upon probation to come up before the doctor for re-examination’ 35. No. of men placed ‘Upon Light duty’ and to come up for re-examination 14. No. of men who have returned, unlikely to completely regain their health, who have now made a start in another profession 34. No. of men who have died since returning to the Force 3’. Cydbwyllgor Sefydlog [Yr Heddlu] Cyngor Sir Forgannwg, cofnodion (GC/SJ/4/2)
Gan fod cymaint o heddweision wedi’u lladd neu eu hanafu tra’n gwasanaethu yn y lluoedd arfog, nid oes syndod bod diffyg heddweision yn ystod y cyfnod yn union wedi’r rhyfel.
Andrew Booth, Cynorthwy-ydd Cofnodion Dros-dro