He saw service with the 3rd, 49th and 58th Battalions on the Western Front and was evacuated to English hospitals on two occasions, first with a broken ankle and later with gunshot wounds to the head and leg sustained at the Battle of Polygon Wood.

Seward was commissioned as a lieutenant in July 1917 but was invalided to Australia in January 1918 as a quartermaster's adjutant on HMAS Euripides.

[2] In the Senate, Seward spoke predominantly on matters affecting rural communities, including the need for better roads and telephones, government promotion of superphosphate and other fertilisers, and standardisation of the railway gauge in Western Australia.

[2] In 1953, he moved a resolution proposing a constitutional convention to review federal–state relations, also suggesting that a portion of the Senate should be nominated by state parliaments "from various groups in the community, such as commerce, local government, and primary and secondary industry".

[5] In 1952, Seward publicly criticised Prime Minister Robert Menzies' agricultural policy on the grounds it did not do enough to support farmers.

[2] He died on 23 July 1958 at St John of God Hospital, Subiaco, aged 74, "after an illness lasting several months".