Things changed in 1604 when James I restored titles and lands to Robert and arranged his marriage to a wealthy Howard heiress. Perhaps this was because young Robert was close to the ill-fated Prince of Wales, Henry Stuart. Unfortunately young Robert wasn’t old enough to actually marry his bride, Frances, so was sent abroad on his own version of 
Robert, the third earl, undertook a military career in continental Europe perhaps to escape the ribaldry. The thirty years war was well under way by this time. He served in the Low Countries and or the Palatinate of which James’ daughter Elizabeth was the queen. In 1625 he was part of the Duke of Buckingham’s disastrous Cadiz Campaign.
It would have to be said that his relationship with Charles was not good. He absolutely refused to pay Charles’ forced loans. And things can’t have been much worse when in 1639 having been appointed as second in command of the the king’s armies in Scotland in the run up to the First Bishop’s War he was demoted so that the role could be given to one of the queen’s favourites. Charles then became a bit sniffy about the fact that the Scots approached the earl to try and prevent the english army from marching north. There was nothing machiavellian in the earl of Essex’s actions that warranted the king’s distrust as evidenced by the fact that Essex handed the letters he’d received from the Scots to Charles unopened. In 1640 he wasn’t offered any role at all in the Second Bishop’s War which must have galled.
In 1640 when the king finally ran out of money and the Long Parliament sat Essex emerged as the principal speaker for the opposition to the king in the House of Lords. He and John Pym worked together to prosecute the Earl of Strafford. Charles, perhaps realising that insulting the earl of Essex in terms of military leadership hadn’t been one of his better ideas offered him a place on the Privy Council in 1641 and by July he was in control of the king’s army south of the River Trent and Lord Chamberlain.
It was Essex who received the news from his cousin Lady Carlisle in January 1641 that Charles intended to arrest five members of the House of Commons and one peer. After that Charles left London for Hampton Court, then Windsor. From there he went north to York. Once in York he ordered the earl to join him but Essex refused and was promptly removed from the post of Lord Chamberlain. Parliament had come to regard him as a potential leader for some time and Charles as evidenced above had never really trusted him. Essex was a bit prickly about his honour having had his father executed for treason so its perhaps not surprising that he chose to side with Parliament rather than the king.
In 1642 Essex was appointed to the Parliamentary Committee of Safety. He also became one of Parliament’s key military figures during the early years of the English Civil War. He wanted to negotiate a peace but from a position of military superiority – his was the middle way if you wish when Parliament was increasingly split between the War Party and the Peace Party.
He commanded the parliamentary forces at Edgehill and as with his continental campaigns he shared the experiences of his ordinary soldiers to the extent that he was actually seen at push of pike. Edgehill was technically a draw but since Essex failed in his objective to prevent the king from marching on London it is usually deemed that he lost the battle. But it was Essex who petitioned Londoners to send as many men as they could to Chiswick on 13 November at Turnham Green and thus ensured that the king withdrew from London rather than be responsible for untold bloodshed.
In 1643 Essex captured Reading but was unable to advance and capture Oxford where the king’s court was based. He became embittered by his armies lack of pay whilst Parliament grew testy about his lack of success. Despite this he raised the siege on Gloucester and won a victory at Newbury.
The king was not alone in mistrusting Essex’s military capacities. When John Pym died in 1643 he was replaced by Sir Henry Vane who was not one of Essex’s fans. A point which seems to have been proved when, in 1644, Essex lost the Parliamentary army in Cornwall and had to escape in a fishing boat. Lostwithiel was the end of Essex’s military career. In addition to the Cornish disaster he had been militarily overshadowed by men like Thomas Fairfax and Oliver Cromwell. He resigned his commission in 1645. Whilst he wasn’t a hugely successful military figure on account of his lack of imagination and flair he was respected by his men because ehe shared their hardships.
The earl of Essex wasn’t hugely successful as a husband either. Having been divorced by Frances Howard he went on to marry Elizabeth Paulet in 1630 having returned from his soldiering in Europe to take up his other career as a politician – and an earl needs a wife. The marriage lasted a year, after that it was a marriage in name only. Six years after they married Elizabeth gave birth to an illegitimate baby which Robert accepted as his own after some hesitation, mainly because he didn’t need the embarrassment of a second errant wife and he did need an heir. The child, a boy named Robert, died when it was little over a moth old and the earl was left without an heir.
