On being informed of the invasion of New Jersey, Washington put his army in motion early on the morning of the day in which Knyphausen marched from Elizabethtown and proceeded to the Short hills behind Springfield, while the British were in the vicinity of that place. Feeble as his army was, he made the necessary dispositions for fighting, but the unexpected retreat of Knyphausen rendered a battle unnecessary. The British were followed by an American detachment, which attacked their rear guard next morning but was repulsed. Instead of returning to New York, Knyphausen lingered in the vicinity of Elizabethtown and on Staten Island, and Washington, unwilling with his inadequate force to hazard an engagement except on advantageous ground, remained on the hills near Springfield to watch the movements of the British army. At that time the army under the immediate orders of Washington did not exceed 4,000 effective men. On the 18th of June (1780), Sir Henry Clinton returned from South Carolina with about 4,000 men, and after receiving this reinforcement the British force in New York and its dependencies amounted to 12,000 effective and regular troops, most of whom could be brought into the field for any particular service; besides these, the British commander had about 4,000 militia and refugees for garrison duty. The British army directed on any one point would have been irresistible; therefore Washington could only follow a wary policy, occupying strong ground, presenting a bold front, and concealing the weakness of his army as far as possible. The embarkation of troops by Sir Henry Clinton awakened the apprehensions of Washington lest he should sail up the Hudson and attack the posts in the Highlands. Those posts had always been objects of much solicitude to Washington, and he was extremely jealous of any attack upon them. In order to be in readiness to resist any such attack, he left General Greene at Springfield, with 700 Continentals, the Jersey militia, and some cavalry, and proceeded toward Pompton with the main body of the army. Sir Henry Clinton, after having perplexed the Americans by his movements, early on the morning of the 23d of June (1780), rapidly advanced in full force from Elizabethtown toward Springfield. General Greene hastily assembled his scattered detachments and apprised Washington of the march of the royal army, who instantly returned to support Greene's division. The British marched in two columns--one on the main road leading to Springfield and the other on the Vauxhall road. Greene scarcely had time to collect his troops at Springfield and make the necessary dispositions when the royal army appeared before the town and a cannonade immediately began. A fordable rivulet, with bridges corresponding to the different roads, runs in front of the place. Greene had stationed parties to guard the bridges and they obstinately disputed the passage, but after a smart conflict they were overpowered and compelled to retreat.