Edmund Ludlow, Memoirs (1894 edition)  

But the very next day the King taking advantage of a very thick mist marched his army within half a mile of Brentford before he was discovered, designing to surprise our train of artillery, (which was then at Hammersmith) the Parliament and City; which he had certainly done, if two regiments of foot and a small party of horse that lay at Brentford had not with unspeakable courage opposed his passage, and stopt the march of his army most part of the afternoon: during which time the army that lay quarter’d in and about London drew together; which some of them, and particularly the life-guard, had opportunity the sooner to do, being at that very time drawn into Chelsey-fields to muster, where they heard the vollies of shot that passed between the enemy and our little party; the dispute continued for some hours, till our men were encompassed quite round with horse and foot; and then being overpower’d with numbers on every side, many brave and gallant men having lost their lives upon the place, the rest chusing rather to commit themselves to the mercy of the water, than to those who were engaged in so treacherous a design, leap’d into the river, where many officers and private soldiers were drowned, and some taken prisoners.  However the enemy’s design was by this means defeated and they discouraged from any farther attempt that night.  The Parliament also were alarm’d in such a manner with the danger and treachery of this enterprise, that they used all possible diligence to bring their forces together, so that by eight of the clock the next morning we had a body of twenty thousand horse and foot drawn up upon Turnham-Green a mile on this side Brentford: those of ours also that lay at Kingston were marching to us by the way of London.  The enemy drew out a party of theirs towards the hill at Acton, which we attacked, and forced to retire in disorder to their main body.  And here again, in the opinion of many judicious persons, we lost, as at Edge-hill before, a favourable opportunity of engaging the enemy with great advantage, our numbers exceeding theirs, and their reputation being utterly lost in the last attempt.  But the Earl of Holland and others pretending to encourage our army by their presence, made use of their time to disswade the Earl of Essex from fighting till the rest of our forces arrived; magnifying the power of the enemy to him, and thereby giving them an opportunity to draw off their forces and artillery towards Kingston, which they did as fast as they could, leaving only a body of horse to face us between the two Brentfords, the rest having secured themselves by a timely retreat; upon this party some of our great guns, guarded by a regiment of foot, were, towards evening, ordered to be fired.  The life-guard was drawn up in the high-ways to secure our foot from any attempt of horse that might be made upon them; which some great men, who pretended a resolution to fight in that troop, blamed, charging the advisers thereof with rashness, in hazarding them in such a pound, where they must inevitably be cut off, if the enemy should advance upon them.  But I fear this great care was counterfeit, and that those persons well knew the enemy to be in a flying, and not in a charging condition, as it quickly appeared; for our cannon no sooner began to play upon them, but they retired to the main body of their army, the rear of which had by this time recovered Hounslow-heath.  The enemy took up their Head-quarters at Kingston, where by advantage of the Bridge over the Thames, they hoped to be able, tho inferior in number, to defend themselves against a more numerous army, if they should be attacked, and to put in execution any design they might have upon the city and places adjacent.  To prevent which our general caused a bridge of boats to be laid over the river between Putney and Battersey, which was no sooner finished but the enemy retired to Oxford by the way of Reading, which place they fortified, and placed a garrison therein, a party of ours having quitted it upon their approach.