The English militia was descended from the Anglo-Saxon Fyrd, the military force raised from the freemen of the shires under command of their Sheriff.

The following year Suffolk reported a total of 19,000 males between the ages of 16 and 60, of whom 9000 were classed as 'able men'; of these, 2600 were selected for training, 1500 others were carpenters, smiths and labourers, and there were just over 100 cavalry.

Suffolk was ordered to assign 2000 men to defend the county's ports and landing places and to send 2500 into Essex to join the Queen's army at Tilbury.

[4][15] A detachment of the Suffolk TBs is believed to have acted as marines aboard the Ipswich ships Corslet and James, which took part in Lord Howard of Effingham's Capture of Cádiz in 1596.

[18] In 1638 the Suffolk Trained Bands mustered 4148 men, armed with 2359 muskets and 1789 'corslets' (pikemen with armour), organised as four regiments of foot, together with a mounted force of 300 cuirassiers.

In the First Bishops' War Suffolk (along with Essex and Kent) supplied both a contingent of pressed men and homogeneous TB companies (1200 men) for Colonel Sir Nicholas Byron's Regiment of Foot and for Sir Simon Harcourt's Regiment of Foot, which was drawn from the Cambridgeshire, Essex and Suffolk TBs.

[19][21] Control of the trained bands was one of the major points of dispute between Charles I and Parliament that led to the First English Civil War.

By now the Suffolk TBs were organised as follows:[19][20] Barnardiston's Regiment was called out briefly in May to put down a riot in Bury St Edmunds.

Despite initial reluctance to cross the county border, the Suffolk regiments (including Ipswich's companies) joined Sir Thomas Fairfax's army on 24 June and participated in the Siege of Colchester.

Under the Commonwealth and Protectorate the militia received pay when called out, and operated alongside the New Model Army to control the country.

[20][32][31][36] During the Third English Civil War, Major-General Thomas Harrison was sent to North West England in April 1651 with a temporary brigade of horse and dragoons recruited for six months' service from volunteers from the militia.

Brewster and Moody's Troops served with Col Nathaniel Rich's Horse in the Midlands, while Sparrow and Moyse's marched with Harrison.

Those from the Eastern Counties were sent to a rendezvous at St Albans on 26 August under Lieutenant-General Charles Fleetwood (to which Blake's composite regiment was also diverted).

As the crisis deepened the St Albans rendezvous was changed to Dunstable on 25 August, the militia to track the advance of the Scottish army as it moved south.

Some of the militia regiments (including the Suffolks) were then sent from this concentration and were involved in the Battle of Worcester, as were the two Troops with Harrison's force and possibly the two with Rich.

These units (mainly troops of horse) were manned by volunteers from the general militia, paid for by subscriptions and by fines on Royalists, and were analogous to the later Yeomanry Cavalry.

Two horse troops were formed in Suffolk in the crisis of March 1655, commanded by John Fothergill and Robert Sparrow, with a third under Humphrey Brewster added in the north-east part of the county in October 1655.