On the evening of August 12, on orders of General Merritt, General Anderson notified Aguinaldo to forbid the Insurgents under his command from entering Manila. On 13 August, unaware of the peace protocol signing, U.S. forces assaulted and captured the Spanish positions in Manila. Insurgents made an independent attack of their own, as planned, which promptly led to trouble with the Americans. At 8 A.M. Aguinaldo received a telegram from General Anderson sternly warning him not to let his troops enter Manila without the consent of the American commander on the south side of the Pasig River. No attention was paid to General Anderson's request that the Insurgent troops should not enter Manila without permission. They crowded forward with and after the American forces and found American and Spanish troops confronting each other but not firing. A flag of truce was waving from the Spanish, nevertheless the insurgents fired on the Spanish forces, provoking a return fire which killed and wounded American soldiers.[16] General Anderson's losses in the taking of the city was nineteen men killed and one hundred and three wounded.[15] General Merrit received news of the peace protocol on August 16, three days after the surrender of Manila.
General Anderson, sent Aguinaldo a telegram, received by the latter at 6:35 P.M., as follows
“ Dated Ermita Headquarters 2nd Division 13 to Gen. Aguinaldo. Commanding Filipino Forces.--Manila, taken. Serious trouble threatened between our forces. Try and prevent it. Your troops should not force themselves in the city until we have received the full surrender then we will negotiate with you.
_Anderson_, commanding.