14 February 1890 – Joined 14th Field Academy Royal Artillery at Shorncliffe as Second Lieutenant.

14 February 1893 – Promoted to Lieutenant.

1894 – Served in Indian mountain battery stationed near Darjeeling.

1897–98 – Employed in the Swat valley and Tirah Campaigns, patrolling the Kurrum Valley.
Awarded medal and 3 clasps.

1 October 1899 – Promoted to Captain.

1899–1903 – Appointed inspecting officer of the Kashmir Imperial Service Troops, stationed at Gilgit near the border of Afghanistan and Chinese Turkmenistan.

11 December 1903 – Departed Sikkim as interpreter, secretary and chief intelligence officer to Sir Francis Younghusband's Lhasa mission as part of British expedition to Tibet.
Awarded medal and clasp.

1904 – Employed former Sengchen Lama's personal attendant Sherab Gyatso to be his personal language teacher and suspected intelligence informant.

21 May 1904 - Fought, and wounded, in battle to capture village of Pala.
David (born Dorje) MacDonald briefly took over O'Connor's interpreter duties during recovery.

1905 –  Posted as the first British Trade Agent at the new Trade Mart in Gyantse, under the Anglo-Tibet Convention.

May 1905 – Investigated theft of remains of Younghusband mission money from boxes left at Gyantse.

Summer 1906 – Stayed with Gertrude Bell whilst she worked on her travel book The Desert and the Sown.

1907 – Import of  two motor cars, by carrying over the Himalayas, into Tibet.
One was an 8hp Clement brought as a gift for Thubten Choekyi Nyima, the 9th Panchen Lama, who presided over Tashi Lhunpo monastery near Shigatse.
The other was his own 6.5hp Baby Peugeot (Peugeot Type 69).

1908 – Accompanied Sikkimese Prince on world tour and also to meet 13th Dali Lama.
O'Connor was the first Indian Government official to meet the Dali Lama.

14 February 1908 – Promoted to Major.

30 September 1909 – Appointed His Majesty's council for the districts of Seistan and Kain.

1910 – Serving in Mashad as Consul-General and Agent to the Governor-General.

1912 – Transferred to Shiraz, capital province of Fars, as Consul.

28 October 1913 – Met with the Edwin Montagu, Under-Secretary of State for India, at lunch arranged by Gertrude Bell, for 1.5 hour briefing and questions on the status of the frontier.

November 1915 – Taken captive by Persian army
14 February 1916 - Promoted to Lieutenant-Colonel.

August 1916 – Released from Persian captivity as part of prisoner exchange.

1918 – Met with Lord Beaverbrook, the Minister of Information and sent to Siberia to further the cause of the Allies and their friends amongst the Russians.

9 April 1918 – Sailed from the Liverpool to New York on board the SS Carpathia.,
taking 11 days, to meet with senior military and diplomats regarding the US policy in Siberia.

3 June 1918 – Arrived in to Vladivostok and served as Resident.

January 1921 – Appointed political officer at Gangtok.

March 1921 – Left position in Gangtok and returned to England, when mother fell seriously ill.

21 December 1921 – Signed Nepal Nepal–Britain Treaty of 1923 as British Envoy at the Court of Nepal.

1925 – Retired from military service.
14 February 1890 – Joined 14th Field Academy Royal Artillery at Shorncliffe as Second Lieutenant.
14 February 1893 – Promoted to Lieutenant.
1894 – Served in Indian mountain battery stationed near Darjeeling.
1897–98 – Employed in the Swat valley and Tirah Campaigns, patrolling the Kurrum Valley. Awarded medal and 3 clasps.
1 October 1899 – Promoted to Captain.
1899–1903 – Appointed inspecting officer of the Kashmir Imperial Service Troops, stationed at Gilgit near the border of Afghanistan and Chinese Turkmenistan. 
11 December 1903 – Departed Sikkim as interpreter, secretary and chief intelligence officer to Sir Francis Younghusband's Lhasa mission as part of British expedition to Tibet. Awarded medal and clasp.
1904 – Employed former Sengchen Lama's personal attendant Sherab Gyatso to be his personal language teacher and suspected intelligence informant.
21 May 1904 - Fought, and wounded, in battle to capture village of Pala. David (born Dorje) MacDonald briefly took over O'Connor's interpreter duties during recovery.
1905 –  Posted as the first British Trade Agent at the new Trade Mart in Gyantse, under the Anglo-Tibet Convention.
May 1905 – Investigated theft of remains of Younghusband mission money from boxes left at Gyantse.
Summer 1906 – Stayed with Gertrude Bell whilst she worked on her travel book The Desert and the Sown.
1907 – Import of  two motor cars, by carrying over the Himalayas, into Tibet. One was an 8hp Clement brought as a gift for Thubten Choekyi Nyima, the 9th Panchen Lama, who presided over Tashi Lhunpo monastery near Shigatse. The other was his own 6.5hp Baby Peugeot (Peugeot Type 69).
1908 – Accompanied Sikkimese Prince on world tour and also to meet 13th Dali Lama. O'Connor was the first Indian Government official to meet the Dali Lama.
14 February 1908 – Promoted to Major.
30 September 1909 – Appointed His Majesty's council for the districts of Seistan and Kain.
1910 – Serving in Mashad as Consul-General and Agent to the Governor-General.
1912 – Transferred to Shiraz, capital province of Fars, as Consul.
28 October 1913 – Met with the Edwin Montagu, Under-Secretary of State for India, at lunch arranged by Gertrude Bell, for 1.5 hour briefing and questions on the status of the frontier.
November 1915 – Taken captive by Persian army
14 February 1916 - Promoted to Lieutenant-Colonel.
August 1916 – Released from Persian captivity as part of prisoner exchange.
1918 – Met with Lord Beaverbrook, the Minister of Information and sent to Siberia to further the cause of the Allies and their friends amongst the Russians.
9 April 1918 – Sailed from the Liverpool to New York on board the SS Carpathia., taking 11 days, to meet with senior military and diplomats regarding the US policy in Siberia.
3 June 1918 – Arrived in to Vladivostok and served as Resident.
January 1921 – Appointed political officer at Gangtok.
March 1921 – Left position in Gangtok and returned to England, when mother fell seriously ill.
21 December 1921 – Signed Nepal Nepal–Britain Treaty of 1923 as British Envoy at the Court of Nepal.
1925 – Retired from military service.
William Frederick Travers O'Connor