In the military events of the first year of the war, Hampden took an active, but subordinate share, as colonel of a regiment of infantry, which he himself raised in Buckinghamshire. Nor did he intermit, as the exigencies of war allowed him, to continue his attendance in Parliament, and to urge there that decisive course of action, which he knew to be necessary to the success of the cause, and laboured in vain to recommend to the Parliamentary general. At the battle of Brentford, his troops, and those of Lord Brook, in support of the London regiment under Hollis, bore the brunt of the day against superior numbers, until the army arrived from London in the evening: and on this occasion (as before at Edge Hill, where he arrived too late to take part in the fight,) he in vain urged Essex to convert, by a decisive forward movement, the doubtful issue of the day into victory. During the winter months, while the king held his court at Oxford, and a Parliamentary army lay between London and that city, Hampden’s regiment was quartered in Buckinghamshire, and his own time was divided between the seat of war and the House of Commons. To this period also, is to be referred the association of six midland counties for the purposes of the war, Bedford, Buckingham, Hertford, Cambridge, Huntingdon, and Northampton; a step which proved of material service in giving strength and union to the Parliamentary cause, and which probably would not have been carried into operation but for Hampden’s peculiar talent of allaying jealousies, reconciling conflicting interests, and smoothing away the obstacles to any business which he undertook.