Lawrence Vincent Moore Cosgrave DSO (2) was born in Toronto, Ontario, son of Lawrence Joseph Cosgrave and Kate Ellen (Forbes) Cosgrave. He graduated from Royal Military College, Kingston, Ontario, and McGill University, Montreal.

At the outbreak of WW 1, Cosgrave was a lieutenant in the Canadian Field Artillery and soon was promoted to captain and then major. Soon after arriving overseas he was serving at the Western Front in France.

By the summer of 1915, the war on the Western Front had stalemated into one of attrition. After the second Battle of Ypres there followed sporadic frontal attacks on both sides without any result other than the slaughter of tens of thousands of men. Conditions were appalling. The troops lived in the squalor and dankness of the trenches, often knee deep in water and mud.

During the second Battle of Ypres, Cosgrave was a captain serving under Major John McCrae, who authored the famous poem In Flanders Fields.

From July 1, 1916, to December 30, 1916, Canadians along with the French and other Allies were involved in the "Slaughter of the Somme", also called the Battle of the Somme. For a pitiable gain of only six miles, 836,000 soldiers were killed, including 24,029 Canadians.

Major Cosgrave earned a Distinguished Service Order (DSO) award for skill and valour prior to November 25, 1916, likely during the "Slaughter of the Somme." His citation reads as follows:

"For conspicuous gallantry in action. He carried out several reconnaissances under very heavy fire, and explored the enemy’s wire in daylight, displaying the greatest courage and ability throughout."

At 5:00 a.m. on April 9, 1917, Canadian forces, in driving snow and sleet and under a barrage of artillery fire, began their assault on Vimy Ridge. An hour later they had taken the first line of enemy trenches and by mid afternoon had captured the crest of Vimy Ridge except for two positions which fell three days later. More than 4,000 prisoners were taken, some of them found chained to their machine guns.

On October 30, 1917 in the mud and driving rain, Canadians carried out their assault on the Passchendaele Ridge and captured it by November 10th. The cost had been horrific: Approximately 16,000 casualties, all for a paltry ground gain of four and one half miles.

The outcome of the war was still in doubt when at 5.00 am on March 21st, 1918, through a blanket of heavy white fog, 64 German divisions attacked the Allied line on a 54 mile front between St. Quentin and Arras. It succeeded in advancing to within 10 miles of Amiens, reaching the Marne River 40 miles from Paris. But by the beginning of June the drive had petered out and the Allies were counterattacking all along the front.

Major Cosgrove earned a second DSO for gallantry prior to April 25, 1918, likely during the German army’s last desperate assault. His citation reads, in part, as follows:

"...When a lorry in the middle of an ammunition convoy was blown up, and six casualties occurred, he supervised the removal of the wounded under heavy shell-fire. By having the lorries nearest the burning one removed, he minimized the effects of the second explosion when two more lorries blew up..."

The Allies made plans for one final assault to end the war. To spearhead it the Canadian Corps was placed in the vanguard. At 4:20 a.m. August 8th, the Canadians charged forward on a front 8,500 yards wide. By nightfall they had advanced eight miles. This was the beginning of the end of the war with the Allies as victors.

After WW1, Cosgrave was Canadian Trade Commissioner at several Canadian embassies around the world. In 1916, he married Beryl Hunter Jones. They had two children: a son and a daughter.