Answer based on context:

Romanian forces continued their advance towards Budapest. On 3 August, under the command of Gen. Rusescu, three squadrons of the 6th Cavalry Regiment of the 4th Brigade entered Budapest. Until midday on 4 August 400 Romanian soldiers with two artillery guns held Budapest. Then the bulk of the Romanian troops arrived in the city and a parade was held through the city center in front of the commander, Gen. Mosoiu. Romanian forces continued their advance into Hungary and stopped at Gyor. The incursion of Romania into Hungary caused the heaviest fighting of the war. The Romanian army casualties were 123 officers and 6,434 soldiers--39 officers and 1,730 soldiers killed, 81 officers and 3,125 soldiers wounded, and three officers and 1,579 soldiers missing in action. As of 8 August the Romanians had captured 1,235 Hungarian officers and 40,000 soldiers, seized 350 guns--including two with a caliber of 305mm--332 machine guns, 52,000 rifles and 87 airplanes.

How many troops and forces are arrived?
bulk of the Romanian troops