1883 Aug 15. Born Guernsey. Thomas Fiott De Havilland (1775-1866), a Lieutenant Colonel in the East India Service, built a large mansion in St. Andrew's Parish ca. 1828, called Havilland Hall. Havilland Hall was later inherited by his grandson John Thomas Ross De Havilland (1852-1907), Jurat of Guernsey from 1882-1907, who was the last De Havilland to sit on the bench of the Royal Court. John passed the mansion down to his son Piers De Havilland, who sold it in 1922 and left Guernsey
1891 census at Vauquiedor Road, St Andrew, Guernsey
1901 census. A Pupil at Elizabeth College, Grange Road, St Peter Port, Guernsey
1902 Jun 4. 4th Leinster 2nd Lt P de Havilland to be Lt
1902 Aug 9 Discharged from hospital in South Africa, 2nd Lt P de Havilland
1905 Jul 21. 4th Leinster Reg. Lt P de Havilland to be Captain
1907 Dec 17. Married Frances Mary Mawson
1908 May 30. 4th Battalion, The Prince of Wales's Leinster Regiment (Royal Canadians), Captain Piers de Havilland resigns his Commission.
1911 census, He and his wife, Frances, of 3 years are boarders at Old Government House Hotel, Guernsey. He is a "job master"
1915 Feb 8. Lands in France
1917 May 4. Leins. R.—Capt. P. de Havilland, Spec. Res., relinquishes the acting rank of Maj.
1917 May 28. R. Dub. Fus. Capt. (actg. Maj.) P. de Havilland (Leins. R., Spec. Res.) to be temp. Maj.
1917 Jun 10 . R Dub Fus. Capt. P. de Havilland (Leins. R., Spec. Res.) to be actg. Maj. while 2nd in comd. of a Bn.
1919 Divorce Court File: 5136. Appellant: Piers de Haviland. Respondent: Frances Mary de Haviland otherwise Frances Mary Mawson. Type: Husband's petition for/of nullity
1919 Feb 9. R. Dub. Fus. The undermentioned relinquish the temp, rank of Maj. on ceasing to be empld. with Serv. Bns. : — Capt. P. de Haviland (4th Bn., Leins. • R., Spec. Res.).
1920 Apr 1. Relinquishes his commission . 4th Leinster R.—Capt. P. de Havilland, and is granted the rank of Maj.
1920 Oct/Dec Married Marie R Barrett in London, known as Dolly
1920 Nov 29. Joined with Auxiliary number 1125. Posted to Depot Coy
1920 Dec 4. Platoon Commander K Coy
1920 Dec 11 He was a "Temp Platoon Commander" with No3 Platoon of K Coy at the Burning of Cork
1921 Feb 5. Posted to O Coy. 2nd in Command
1921 Feb 17. Posted K Coy. Promoted O/C K Coy . This was a response to the need for a Coy Commander of K Coy after Latimer had been suspended as a result of the burning of Cork.
1921 Feb 28. Posted to O Coy. O/C O Coy . K Coy was wound up at this point
1922 Jan 31. Discharged on demobilisation of ADRIC
His father applies for his medals in 1923, indicating that he was not in UK. From the death notice, he may have been in India
1937 Oct 21. Died Kensington, London age 54, of pneumonia